# Physics 11 – Newton’s Laws

This first video represents Newton’s first law: Inertia. An object will stay in motion, and an object at rest will stay at rest. I used the cart to show an object in motion. According to Newton’s law, in perfect conditions, the cart will never stop rolling after I push it, but it will stop due to friction slowing it down (in the video it hit something). I used a weight to show that it will take more force to get the object to start moving, if I used more force it would have moved.

The second video represents Newton’s second law: F=ma. This law shows the relationship between Net Force, Mass, and Acceleration. You can use this equation to calculate how much force it would take to accelerate an object with a certain mass at that speed. I used two pineapples with different masses. To get both of the pineapples to accelerate at the same speed I would need to apply more force to the heavier pineapple. If I were to use the same force on each of the pineapples, the smaller one would accelerate faster than the larger one. Another example, is if you had two cars, one heavier than the other, it would take more force to move the larger car at the same speed of the smaller one.

This last video shows a example of Newton’s third law: F1=-F2. Every action will have an equal and opposite reaction. With an object resting on the ground, you would have the force of gravity pushing downwards, and also the normal force, equal to the gravitational force, holding the object up. In my example, I used a ball of silly putty to show the opposite force, when the ball hits the desk, it bounces back upwards. But then why, for example, does my textbook not bounce when I drop it? The bouncing happens die to the elasticity of the object, it depends on the objects ability to deform and reform upon impact, even if the object does not bounce, the upward force is still there.