Question

Which of the following energy conversion is observed when a body at rest rolls down on an inclined plane?
1. gravitational potential energy → linear potential energy
2. gravitational potential energy → rotational kinetic energy
3. linear kinetic energy → rotational kinetic energy
4. translational kinetic energy → linear potential energy

Answer 1

Correct Answer - Option 2 : gravitational potential energy → rotational kinetic energy

The correct answer is option 2) i.e. gravitational potential energy → rotational kinetic energy

CONCEPT:

• Rotational kinetic energy: Rotational kinetic energy is due to the motion of an object's rotation.

For a given fixed axis of rotation, the rotational kinetic energy is given by:

\(KE = \frac{1}{2} Iω^2\)

Where I is the moment of inertia, ω is the angular velocity.

EXPLANATION:

• The rolling motion is a combination of translation and rotation.
• An object at rest before rolling will be at a certain height from the surface of Earth. Hence, it will have gravitational potential energy.
• As soon as the body starts rolling, its gravitational potential energy is converted into translational and rotational kinetic energy. 
• According to the given options, the gravitational potential energy is converted into rotational kinetic energy.