Which scenario best illustrates rotational kinetic energy?

• A. A wheel spinning
• B. A car driving in a straight line
• C. A ball rolling
• D. A person running

Answer: (A)

Rotational kinetic energy is the energy an object has due to spinning around an axis, depending on how fast it spins and how its mass is distributed. A wheel spinning in place shows energy stored purely in rotation about its axis, with no need for forward motion. The wheel’s angular velocity and its moment of inertia determine how much energy is in that rotation. In contrast, a car moving straight primarily has translational kinetic energy from linear motion; a ball rolling has both rotational and translational energy because it spins while moving forward; a person running mainly involves translational energy of the body’s movement. So the wheel spinning best illustrates rotational kinetic energy.