# Newton’s Second Law of Motion

Isaac Newton, a great scientist who discovered the basic laws of motion, is the founder of Newton’s Mechanics. Several well-known experiments prove Newton’s second law of motion. It demonstrates that force equals to the product of mass and acceleration.

In order to decrease the friction from the environment, Jerry stands on a skateboard and pushes himself against the wall. Firstly, Jerry pushes against the wall hard and the distance he rebounds will be recorded. Secondly, same process will be repeated except that, this time, Jerry will push against the wall with a smaller force. Then the results will be compared. When he pushes against the wall strongly and exerts as much strength as possible, he moves back for about 6 meters. However, when he pushes with a smaller force, he just moves back about 0.2 meter. Jerry repeats this experiment for 5 more times to ensure the precision. Comparing the two groups of data, it shows that when the force exerted on an object increases, the acceleration of this identical object will increase. Furthermore they are directly proportional according to Newton’s second law of motion. The data also proves they are directly proportional.

For the second experiment, the changed variable is mass. Jerry will push against the wall for twice with the same force but in the second time, he will take a 20 kg backpack. To ensure he exerts the same amount of force, he will push the wall with his maximum strength. After repeating the experiment several times, the data suggests that when Jerry pushes against the wall without an extra mass, he moves back for about 6 meters. However, when he carries a 20 kg backpack, he only moves back 4 meters. Additional experiments will added at the end. Jerry carries different weights of backpack and repeats the same procedure. Those experiments shows the relation between the object’s mass, force, and acceleration. The result suggests when the mass of an object increases, the acceleration of this identical object will decrease. Moreover, they are inversely proportional.

Since when Jerry pushes against the wall, he will move back. This demonstrates that direction of motion is opposite to the direction of net force.

In our daily life, we can find a lot of examples that illustrates Newton’s Second Law of Motion. For example, sprinters always step hard on the ground in order to gain the maximum acceleration. F-1 race cars weigh light (decrease the mass) to increase the acceleration. Newton’s second law of motion can be applied in many fields.