Question

5/10
how does air resistance affect the energy of a falling ball?
it decreases the potential energy.
it has no effect on the energy.
it increases the kinetic energy.
it converts some energy into thermal energy.

Explanation:

When a ball falls, air resistance acts as a non - conservative force. According to the law of conservation of energy, the total mechanical energy (sum of potential and kinetic energy) is not conserved in the presence of non - conservative forces. Air resistance does work against the motion of the ball. The work done by air resistance is dissipated as heat (thermal energy). Potential energy \(U = mgh\) depends on the height \(h\) of the ball. As the ball falls, its height decreases, so potential energy decreases regardless of air resistance (this is due to the change in height, not directly because of air resistance). Kinetic energy \(K=\frac{1}{2}mv^{2}\). In the absence of air resistance, all the loss in potential energy would be converted into kinetic energy. But with air resistance, since some energy is lost as thermal energy (\(E_{th}\)), the kinetic energy of the ball is less than it would be in a vacuum.

Answer:

It converts some energy into thermal energy.