Find the energy dissipated by frictional forces when the car moves down from X to Y.

Answer: Option B

Using conservation of energy (COE), the total energy of the car at X = total energy at Y.

At X, the car only has gravitational potential energy. If there is no friction, the magnitude of the kinetic energy must be equal to the GPE at X.

But since there is frictional force, there will be some energy wasted as work done against friction, usually in the form of internal (thermal) energy and sound energy.

Hence, GPE at X = KE at Y + WD against friction

Refer to the video explanation