9) Because of friction A) energy is NOT always conserved. B) NOT all potential energy is converted to kinetic energy. C) all of an object's kinetic energy turns into potential energy. D) all of an object's potential energy turns into kinetic energy.

Hello!

The answer is: B) NOT all potential energy is converted to kinetic energy

Why?

Let's discard each option in order to find the correct option:

A) energy is NOT always conserved, False: Energy is always conserved, energy can turn to another kind of energy but the energy will be always conserved.

B) NOT all potential energy is converted to kinetic energy, True: We must remember that Energy of Friction usually opposes to the movement of a body, so, it means that all the potential energy (work) applied to an object would not be converted into kinetic energy (movement).

C) all of an object's kinetic energy turns into potential energy, false: Since the Energy of Friction is acting, not all of the kinetic energy will be turned into potential energy.

D) all of an object's potential energy turns into kinetic energy, false: Since B is true, D is false, not all potential energy is converted to kinetic energy because of the energy of friction.

Have a nice day!

The right choice is (B) NOT all potential energy is converted to kinetic energy.

Explanation:

Friction is a repulsive or resistive force to motion of any body in motion. When two bodies move against each other some of the kinetic energy is converted to heat energy due to friction. This reduces the total kinetic energy in the system. In other words we can say that when two contacting surfaces move relative to each other, the friction between the two surfaces converts kinetic energy into thermal energy, or heat.