A man with a mass of 75 kilograms is standing on a roller coaster platform. As the roller coaster begins to move, the man notices that his weight feels lighter than it does when he's standing on the ground. Why does the man feel lighter on the roller coaster compared to when standing on the ground?
A. Decreased gravitational force on the man
B. Increased gravitational force on the man
C. Increased normal force exerted by the platform
D. Decreased normal force exerted by the platform
E. No change in the apparent weight of the man because the roller coaster is accelerating.
The correct answer is D. Decreased normal force exerted by the platform.
To understand why the man feels lighter on the roller coaster, we need to consider the forces acting on him. On the ground, there are two main forces acting on the man: the gravitational force pulling him downward and the normal force exerted by the ground pushing him upward. These two forces balance each other out, resulting in the man's weight, which is the force with which he is pulled toward the center of the Earth.
When the roller coaster begins to move, it accelerates, which means the velocity of the roller coaster changes. According to Newton's second law of motion, an object will experience an acceleration when there is a net force acting on it. In this case, the acceleration of the roller coaster leads to a change in the forces acting on the man.
As the roller coaster accelerates, it starts to exert a smaller normal force on the man compared to when he is standing on the ground. This is because the normal force adjusts to counteract the acceleration. The downward gravitational force remains the same, but the upward normal force decreases, resulting in a net force that is smaller than the man's weight.
Since the man's weight is not fully counteracted by the normal force, he will feel lighter on the roller coaster compared to when he's standing on the ground. This sensation is often experienced as a feeling of weightlessness or reduced weight.