Unit 3 Reflection

During this unit of physics we covered from newton’s third law to the law of conservation of momentum. I enjoyed this topic of physics since it was easy to comprehend and had may relations to the physical world. This unit also allowed me to explore new paths of physics such as gravitational forces and how they affect our tides. On the first day of this unit the class was prompted with the question: “In a crash, who exerts a larger force on the other: a car or a truck?” In order to solve this problem and justify your answer you must understand newton’s third law. Newton’s third law states that ever action has an equal and opposite reaction. Newton discovered that if a force is exerted from object A onto object B, than Object B would exert and equal and opposite force onto object A. Since we know this it is impossible for one object to exert a greater force on the other. Both the car and truck will exert an equal and opposite force onto each other. If this is true, then why will the smaller car usually move backwards when hit by a big truck? Similar to a horse and buggy the horse pulls the cart forward; while the cart pulls the horse backwards (this is called an action-reaction pair). The cart will eventually move since it exerts a greater force onto the ground than the wheels on the cart. The cart moves forward since the horse pushes ground backwards and ground pushes horse forwards. This is also how a tug of war team wins. The winning team wins the competition since they exert a greater force on the ground than the opposing team. During this unit we also learned about vectors. A vector is a mathematical term showing both direction and magnitude. We use vectors in physics when there are two forces that are not in the opposite or same direction as each other. Picture you paddling across a river. You paddling allows you to move across the river while the current pushes the boat down the stream. We can represent this with two vector arrows, one in the vertical and one in the horizontal direction. Since the boat is experiencing a downward force from the current, the boat will not travel straight across the river. This is depicted in the picture in my blog. While the boat is on a heading for position A it will actually reach position B due to the force of the current pushing the boat downwards. Our picture shows the horizontal and vertical vectors as dotted lines and the actual force vector as the red line. When solving for actual force we use the fundamental equation a2+b2=c2. Using vectors, why does a box slide down a ramp? A box has a force of weight also known as gravity acting on it. This force of gravity is demonstrated through line 1. This is the first line when solving this problem. Our next line will be equal in magnitude to line 1 but in the opposite direction. We use this line to create our third line known as the guide line. Our third line will be our guide line. This line will go above our second line and help us when creating our support force for the box situation. Once we have finished the guide line we draw a line that starts from the center of the box until it hits the guide line. This line is green and is known as the support force. We then draw our vectors since this is a free body diagram. The vector lines are shown in grey. We are then able to finish and draw the resulting vector which is the purple line. This diagram shows why a box will go down a ramp. Next we learned about gravitational forces and physics. Everything in the universe that has a mass also has a gravitational force. The larger the mass, the larger the gravitational force. This is why the planet earth rotates around the sun rather than the sun orbiting the earth. The formula we use to calculate the gravitational force is; Universal Gravitational Formula = G((Mass of first object + Mass of second object)/Distance between both objects squared) F=(G)((M1+M2)/d^2) Since the gravitational force is so weak we add G which is equal to 6.67 x 10-11 Nm2/Kg2. From the formula we can determine that mass is proportional to gravitational force and inversely squared proportional to distance. Tides are produced due to the difference in force on either side of the planet. Since the ocean surrounds the world. One side of the planet will experience a different gravitational force than the other. This is how tides are produced. The moon orbits around the earth causing 2 high tides and 2 low tides every day. We also experience spring and neap tides. A spring tide occurs when the moon and sun are on either side of the earth, this produces very high, high tides and low, low tides. A spring tide occurs when the moon is perpendicular to the sun. This causes higher low tides, and lower high tides. Other bodies of water don’t experience tides since they aren't big enough to experience a difference in force. Momentum is defined as inertia in motion. Momentum is defined as the product of the mass of an object and its velocity. The equation for momentum is; Momentum= mass x velocity P= mv You may be wondering if a skateboard can have a larger momentum than an aircraft carrier. At first I thought that the answer was obvious but soon found myself wrong. A skateboard although small in mass can have a positive velocity. If the aircraft carrier is at rest than it doesn't have a velocity and therefore no momentum. Astonishingly, this means the skateboard has a larger momentum than the aircraft carrier. From momentum we get impulse. Impulse is force multiplied by the time the force is applied. The equation is as follows; J=F∆T We can use this equation when understanding how an airbag protects us from being hurt. When in a car accident the airbag will deploy. This occurs to reduce injury from the collision. The car goes from moving to not moving during the collision. The change in momentum is the same if we hit the airbag or the dashboard. If change in momentum is the same, than impulse (J) is also the same whether you hit the airbag or the dash board since J is the same (∆P=J). Airbags will therefore increase the time and decrease the resulting force. We can represent the difference between the airbag and the dashboard through the equations below: J = F∆T - Airbag J = F∆T – Dashboard The law of conservation of energy states that energy can neither be created nor destroyed, only transformed. Due to this law, any energy in a system will never diminish, only transfer. If a small car hits another small car at rest and they stick, then both the cars will move with a slower velocity however the momentum will be conserved since there is a greater mass. The law of conservation of momentum can be depicted as; ∆P = PFinal – PInitlal FA = -FB

FA∆T= -FB∆T Thank you for reading my blog and I hope you found it useful and enjoyable!

Tides in Bermuda

You may be wondering how tides happen in our world? Before we answer that question we must know that there are four different tides every day. There are two high tides and two low tides every single day. This happens because of the gravitational pull of the moon. The moon is pulling the earth equal and opposite to the gravitational force. Different tides occur throughout the day since the moon rotates around our planet. Think of a tug of war between the moon and the earth. Tides occur because of the gravitational force of the moon. In the photo bellow it is interesting to notice that the seaweed is higher than the water line. The seaweed is so far up the beach because the high tide pushed it there. That means there is a low tide currently. A really high tide will occur during a full moon and a very low tide will occur during a new moon. To answer our initial questions tides are caused by the difference between the forces on each side of the earth.

Impulse and Momentum

I decided to use this video on impulse and momentum since it includes an example when explaining the concepts. The video also incorporates very important formulas for this topic such as the formula for momentum and impulse. The video explains the relationship between impulse and time. P= F x Change in T. The video explains that if a force is applied for a longer time period, the impulse will increase. The home run hit is an example of how impulse and momentum is seen in typical life.

Riding the Waves

The youtube video offers a cartoon visual when discussing the tides that exists on our planet. The video goes into detail about why the oval shapes around our world. It also talked about high tides and low tides. The video discusses gravitational force and how it affects us. The video briefly touches on the distance squared rule when he uses a water hose as an example. This is the most commonly forgotten rule when applied to the gravitational force equation. I liked this video a lot since it also discusses certain scenarios such as the earth being too close to the sun.

Unit 2 Reflection

During this unit we learned about free fall, projectile motion and falling through the air. Many of these are considered hard topics but are surprisingly easy to understand. Newton’s second law is very important to know for this topic. This law states that acceleration is proportional to force and inversely proportional to mass. We can derive an equation stating a=f/m. It is important to know the objects mass rather than its weight! We will now look at what physics are in play when throwing a ball upward. You may be thinking to yourself that if you drop different objects with different weight they will hit the ground at the same time. In our world this may be true however in a vacuum, were air resistance is negligible, both the objects will hit the ground at the same time. This is known as free fall. Free fall is when air resistance is negligible therefore the only force acting on an object in free fall is gravity. This means that in a vacuum, if you dropped a bowling ball and a feather they would both hit the ground at the same time! Weird right? When we throw a ball straight up it has an initial velocity. When the ball leaves your hand the force of gravity is constantly accelerating the ball in an opposite direction. This is why the ball will begin to slow down at the top of its path. If a ball is thrown in the air for with an initial velocity of 40 m/s how long is the flight time? You may want to draw a diagram to help with this problem; The diagram here shows that the ball is in the air for 8 seconds. When the ball is released gravity pulls the ball to the ground therefore the velocity decreases by 10m/s every minute. When the ball reaches the top of the path it accelerates and will hit the ground with the same velocity when it was thrown. In order to calculate the maximum height of this problem we use the equation; d=.5(g)(t)2. It is important to remember that this formula only works when an object is going downward/start with a velocity of 0m/s. Because of this we start when t=4. Since we are calculating the maximum height our t in this case would be 4 seconds. Now consider a ball is released from a height, undergoing free fall, but is moving in the horizontal direction. An example of this is an airplane dropping a bomb (sorry). When released, the bomb still only has one force acting on it. This is the force of gravity. However, since the bomb was moving in the horizontal direction, we know that an object in motion wants to stay in motion! This means that the bomb will have a constant velocity in the horizontal direction and a constant force of gravity in the vertical direction, It is important to remember that the vertical velocity and the horizontal velocity are in-dependent from each other. If a bullet is fired and a bullet is dropped at the same height and at the same time which will hit the ground first? They both would!! This happens because although the bullet fired covers more distance in the vertical direction, it still undergoes the same force of gravity as the bullet dropped. Pretty crazy stuff!! This is why snipers always aim higher than the target. This is known as ‘bullet drop’. Now to calculate the vertical distance an object travels for projectile motion we use the formula d=.5(g)(t)2. We need to know the time the object is in the air in order to calculate the horizontal distance. We do this because the object is in the air for a certain amount of time therefore it will travel at a constant horizontal velocity during that time. We calculate this by using the equation v=d/t. We use the same time that the ball is in the air for in this equation.

Now in our world we don’t experience free fall. This only occurs in a vacuum where air resistance is negligible. When we are falling through the air we experience air resistance. When a skydiver jumps out of a plane, he will accelerate due to the force of gravity also known as his force of weight. As the skydivers velocity increases so does his air resistance. Therefore we can say that air resistance is directly proportional to velocity. The initial acceleration of gravity is 9.8 m/s2. This acceleration will decrease due to the opposing force of gravity acting upon the skydiver. The skydiver will eventually reach a point of equilibrium where his force of air resistance is equal and opposite to his force of weight. This point is referred to as terminal velocity. In many James Bond movies we see the hero moving through the sir by changing his body position. This actually happens! If we change our surface area we change the air resistance. By reducing you surface area you are able to reduce your air resistance. If you increase your surface area, your air resistance will also increase. When a skydiver deploys his parachute he is increasing his surface area. This causes him to get in increase in air resistance and therefore he accelerates in the opposite direction. This causes the skydiver to slow down. The skydiver wants to get back to equilibrium so he will eventually slow down to a point where the force of air resistance is again equal this force of weight. The net force acting on him is the same however his velocity has changed. I know this may seem strange but it is true physics! Know why does a crumple piece of paper hit the ground before a flat sheet of paper? It is because of the difference in air resistance. The flat sheet of paper has a higher surface area therefore the sheet of paper is unable to gain as much velocity as the crumpled sheet of paper. If a lead ball is dropped of a building and a Ping-Pong ball is dropped of the same height, which will hit the ground first? If you said the lead ball you are correct! This happens because the lead ball has a higher force of weight than the pin pong ball therefore it will take longer for the air resistance to be equal and opposite to its weight. This will allow the lead ball to have an increased terminal velocity than that of the Ping-Pong ball.

Objects Falling with Air Resistance Resource

This video was great! It explains the concepts of air resistance that isn't too advances for us however towards the end the video begins to discuss material that we have not covered. The video explains air resistance using graphs which allowed me to understand air resistance through math. The video also explains the difference between having air resistance and the absence of air resistance.

Projectile Motion picture

I hope you recognize this photo! It is our projectile motion lab. We had to predict the distance a ball would travel only knowing the height in which the ball would fall. This proved to be a difficult task since we had to translate our information and predict where the ball would fall. In the picture above the ball has just left the ramp and is about to strike the paper. This photo graph demonstrates projectile motion since the ball is moving with both a constant horizontal velocity and an increasing vertical velocity. For this experiment we needed to find the horizontal velocity since it will remain constant. Once we discovered the horizontal velocity we needed to calculate how long it would take the ball to fall. When discovering the time we were able to calculate the balls horizontal distance. This picture shows someones prediction and the ball hitting the paper!

Projectile Motion Concepts

I liked this Projectile Motion video a lot since it walked you through all the steps. This video uses an example and explains the laws surrounding Projectile Motion. The video explains that the horizontal velocity and vertical velocity are independent and don't rely on each other. It give multiple of example of how this statement is true.

Projectile Motion Concepts

I liked this Projectile Motion video a lot since it walked you through all the steps. This video uses an example and explains the laws surrounding Projectile Motion. The video explains that the horizontal velocity and vertical velocity are independent and don't rely on each other. It give multiple of example of how this statement is true.

Newton's Second Law of Motion

This video explains Newtons Second Law of Motion. I like this video a lot since it gives you the formula in a forum than what I was previously taught. The video represents Newtons Second Law as F(force)= m(mass)x a(acceleration). The video teaches this law in an organized and easy method great for supporting and re learning material!

Unit 1 Reflection

In this introductory unit to Physics, I learned about basic concepts. I learned about forces and different concepts from both Newton and Galileo. This unit covered inertia, velocity and acceleration and all of the properties surrounding them. Initially I thought of Physics as a scary topic due to my past experience however after this first unit I have become less terrified of the idea. In this introductory unit I learned that physics is what surrounds us. It occurs in our everyday life eg/ walking, jumping, driving.. I was taught basic physics in Bermuda and was introduced to more difficult concepts such as simple harmonic motion and projectile motion. In this unit I re-learned concepts regarding acceleration and velocity and how they differ. Velocity is directional speed whereas acceleration is in increase or decrease in speed over a unit of time. To introduce newton’s first law of motion; every object in motion will stay in motion at uniform speed unless acted on by an outside force. So why does a car gradually slow down on the road? It is because friction slows the car down. When we remove this force with a hovercraft, once in motion, the hovercraft will travel at uniform speed unless acted on by an outside force. Since friction is present in our world it is impossible for an object to move at uniform speed unless it is counteracting the force of friction. Another interesting theory we went over is the significance of head rests and how they help when we suddenly go forward. Interestingly enough, since the car suddenly goes in motion our head want to stay at rest. Since our head wants to stay at rest the headrests prevents us from damaging our neck. Similar to a ball thrown up in the air, it will keep moving up simply because nothing is preventing it from going up. Our head will fall back unless something prevents our head from falling back. A race car driver wins a race through acceleration. Acceleration is the change in speed over a unit of time. The formula to express this is; V=at (Velocity= acceleration x time) The race car driver also wins the race since he/she is maintaining higher velocity than the other race car drivers. The velocity will change once the direction has changed. For instance if the race car driver turns around a curve, the car is momentarily accelerating and changing velocity since the direction is being changed. Constant velocity is the constant speed of an object. Constance acceleration is the constant increase in speed over a certain amount of time. The equation to calculate the distance of an object traveling at a constant acceleration is as follows; d=.5(a)(t)2 (distance=.5(acceleration)(time)2) I have learned that an easy way to solve a physics problem is to understand the variables in the question. The trip problem demonstrates a classic example of how our brain works. When we are provided with numbers we tend to overlook important aspects in the problem. It is vital to underline all variables present in the problem. Here is a problem that people tend to mess up on; What is your acceleration if you drive 60mph for 1 hour? The answer is that you are not accelerating since you are traveling at a constant velocity. Do you see how it is easy to become overwhelemed when presented with numbers. To solve this problem, write the acceleration formula and the corresponding unit. You will quickly realize that you cannot solve it since you do not have a value for acceleration. I found this difficult to comprehend initially since I was presented with numbers. I overcame this problem by using the technique mentioned earlier. Writing out all the variables and the formula for the unknown is an easy method to overcome this problem. This allows you to visually see the unknown variables and what needs to be solved. My goal for the next unit is to overcome this problem of mine and to not let any question confuse me. I plan to use this method on any problems I find confusing. We studied constant acceleration, constant velocity, newton’s first law and many other concepts. All concepts have real world application. An example of constant acceleration is a plane taking off at full throttle. The plans speed is accelerating constantly per unit of time. An example of constant velocity would be a ball rolling on a flat plain. Newton’s First law of motion can be demonstrated through a hovercraft of the movement of asteroids. All occur every day in and outside of our world. For more information regarding constant velocity click on the you-tube video!!

Constantly Accelerating, not at a Constant Velocity!

The purpose of this lab was to determine the difference between constant acceleration and constant velocity. Both constant velocity and acceleration are normally misunderstood and therefore it is necessary to achieve a full understanding of the difference. Constant velocity is when an object is moving at uniform speed. The velocity of the object is constant and therefore the object is at equilibrium. The object is covering the same amount of distance per second, assuming that no force is acting against it (eg./friction). Constant acceleration is the opposite of constant velocity. Constant acceleration is when an object is accelerating at an equal speed with time. While constant velocity moves at a uniform speed, constant acceleration increases speed. In the lab we determined constant velocity and acceleration by using two experiments. One of the experiments took place on a flat plain. This allowed the marble to move at a constant velocity once released by the ball thrower. Once the ball begins to move, for every half second, make a mark with a piece of chalk on the table. Record your data keeping in mind that the distance is cumulative! Plot your data into Microsoft excel and plot the data on a scatter chart. Your graph should resemble a straight line. For the second experiment, place two books of equal width, under the two end legs of the table. This will create an inclined plane. For this experiment it is necessary to release the ball on a start line exactly when half a second has passes. Once the ball begins to roll, make a mark with the chalk at every half second point. This experiment will also require accumulative distance for the outcome to be correct. Once you have plotted a scatter chart you should notice a curve in the line. With constant velocity, the ball is covering the same distance per unit of time while constant velocity increases the distance covered per unit of time. In order to calculate the speed of constant acceleration we use the formula V= Acceleration x Time. In order to derive the distance we use the formula D=0.5(Acceleration)(Time)2. To calculate constant velocity we use the formula Speed= Distance/Time. The line for constant velocity is a straight line while the line for constant acceleration is an upward curve. The y-axis of the graph is distance while the x-axis is time. I learned that the equation of a line is; Y=mx+b (b is normally always going to be zero) Distance=(m)(Time) (we get this when substituting our y and x) M=Distance/Time (altering the equation we get this!) It is safe to say that our m in this case represents speed. We were able to derive the speed formula from utilizing the formula of a line. We were also able to create an equation for discovering the distance covered at constant acceleration by using the line equation; Y=mx + b(0) D= (0.5)(Acceleration)(Time)2 (our m in this case is the slope of our line while the x is time) This magical journey through Physics has taught me the combination of math and physics. I have also learned that the line equation was not made to just torture us but to help guide us through other subjects. This lab has also taught me how to incorporate a graph and explain a physics problem using math.

Going on a Trip!

The Trip physics question is both interesting and annoying! The question goes like this; "A motorist wished to travel 40 kilometers at an average speed of 40km/h. During the first 20 kilometers, an average speed of 40km/h is maintained. During the next 10 kilometers, however, the motorist goofs off and averages only 20 km/h. To drive the last 10 kilometers and average 40 km/h the motorist mist drive: a.)60km/h b.) 80km/h c.) 90km/h or d.) faster than the speed of light? My initial guess at the problem was 80 km/h since the motorist drove half of the average speed. Since the motorist drove at a speed of 20km/h for 10 km I assumed that she would have to drive 80 km/h to make up for lost time. This answer was incorrect. Although I was on the right path, I wasn't seeing the full picture. I missed the aspect of time and began to re-think my answer. I used the equation speed=distance/time. I rearranged this equation to discover the time and was shocked at my discovery. Since the motorist drove 40km/h for 20km the motorist drove for 30 minutes. I then discovered that the motorist drove at 20km/h for 10km indicating another 30 minute time interval. The motorist traveled 30km in an hour and initially wanted to travel 40km in one hour. This means that the motorist has to travel 10km instantaneously, faster than the speed of light. The speed formula can be manipulated to derive either the distance or the time and object has traveled when given the speed, distance or time. In this case you would rearrange the speed formula to time = distance/speed. I approached this problem trying to discover the average speed and was overlooking the time aspect. This problem has taught me to factor ALL variables and pay attention to little details in the equation. I will remember to underline all the variables discussed in the question in future problems.

Accelerating through Physics

Galileo developed the concept of acceleration in his experiment of inclined planes. He noted that a ball rolling down an inclined plane will increase speed up to the same amount of speed in successive seconds. Speed is a scalar quantity that indicates how fast an object is moving. Velocity is the rate at which an object changes its motion. Galileo's concept is now known as acceleration. Acceleration is the rate of which velocity changed with time. The formula for acceleration is; Acceleration (A) = Change in Velocity/ Distance. Velocity and acceleration may seem similar but are the exact opposite. By walking in a circle I am constantly changing my velocity since I am changing my direction. Acceleration is the change in velocity divided by the distance. An example of acceleration is a car at rest that speeds up to 20 miles/h. The car is therefore accelerating. It is also very important to note the units of measurement for acceleration and velocity. Velocity is always measure in meters/second. If the velocity of an object changes than the object is said to be accelerating. An important rule to remember is when an object begins to slow down, it is still accelerating but in an opposite direction. If an objects velocity is changing constantly, the object is still accelerating however if the object is moving with a constant velocity than the object is not accelerating. Acceleration is usually measured in M/S2 (meters/second squared). I chose to include a website that explains the concept surrounding velocity and acceleration. I decided to use this website because it exposes the viewer to animation that helps develop more of an understanding. The website also describes the concept of an object slowing down; it is accelerating in an opposite direction. This is a very important concept that confused me at the beginning of the year! http://www.physicsclassroom.com/class/1dkin/u1l1e.cfm

Hovercraft Mayhem

Although I was unable to participate in the hovercraft ride I was surprised by the reaction that it had on my class mates. When the hovercraft was first displayed I found it hard to believe that a leaf blower, a piece of wood, and some plastic was going to prove how newton’s first law of motion works. I was surprised by the amount of noise the hovercraft emitted but was also surprised to see the hover craft work! The hovercraft really allows you to experience newton’s first law of motion first hand. Newton’s first law of motion is that ‘every object continues in a state of rest or uniform speed in a straight line unless acted on by a nonzero net force’. The hovercraft echoed this theory since it neutralized friction by hovering above the ground. This allowed the hovercraft to stay in uniform speed. The hovercraft will neither accelerate in a positive or negative direction without an outside force being added on the hovercraft. This is much different than items such as sleds, or skateboards. During this experiment I learned that when the hovercraft was in motion there was a net force of zero. I also learned that at this stage the hovercraft is in a state of equilibrium. When the hovercraft is pushed into motion by another force, it accelerates and has a net force acting on the hovercraft. This also means that the hovercraft is not in equilibrium until the force is not pushing the hovercraft. Acceleration depends on a force acting on the object. During the lab it became apparent that some individuals were harder to stop than other members. This is due to their mass. An individual with more mass will be more difficult to set into motion that an individual has a smaller mass. It was easier to put a student with a smaller mass into motion than a student with a larger mass.

Inertia and Mass!! Great Website

That wasn't too bad! Learning about inertia was a little difficult however the worksheet seemed to be impossible to understand. After going on the website bellow I was able to fully understand Newton's First Law of Motion and Inertia! The website explains that it is not normal for objects, once moved, to stop and return to its natural rest. The website allowed me to explore this idea. I think of the theory as one rolling a ball on a flat plain. The ball will stop moving because it is experiencing friction however if we did the same experiment where friction was absent than the ball would constantly move. I also learned that if an object has more mass, it also has more inertia since it is more resistant to change its state of motion. The website also offers some fun, interactive questions at the end to further develop the concept of inertia. Click on the link to learn more about inertia!! http://www.physicsclassroom.com/class/newtlaws/u2l1b.cfm

Day 1 (intro to Physics)

Stepping into the class room I was reminded of my past experiences with Physics. In Bermuda I enrolled in a Physics Higher Level course for the IB program. Although I did not have a 'fun' time with physics in Bermuda, I enjoyed understanding different theories. During my studies in Bermuda I learned about simple harmonic motion, projectile motion and the properties of work and power. I was exposed to this material on a standard level and on a higher level. Some information became difficult to understand due to missing variables. Projectile motion proved to be very challenging to comprehend. I also learned about all of newton’s laws and linear momentum. I have a basic idea about waves, and wavelengths.  I am interested in what causes the oceans tides. Although I am aware that the moon influences the oceans tide I do not understand Einstein’s theory of relativity and space. I am interested to learn certain theories such as Einstein’s theory of relativity. I briefly studied light and prisms in Bermuda however I am best with Specific heat and waves/wavelength. I am also excited to learn about how our position can alter our velocity eg: an ice skater spinning. I am interested in pursuing a career in the aviation field which involves a large amount of physics. I hope to become a pilot, either for the military or public. I plan on studying aeronautical engineering and aviation in the field of physics.  Although I have had some difficult experiences with physics I am looking forward to this year of physics in Asheville!