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