A student investigates how friction affects the energy of a mechanical system
PHYSICS · Subjective · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A student investigates how friction affects the energy of a mechanical system.
(i) State the work–energy theorem for a particle moving under the action of external forces.
(ii) Define a conservative force and a non-conservative force, giving one example of each.
(iii) A block of mass m slides a distance d on a horizontal rough surface with coefficient of kinetic friction μk after being launched with speed v0. Qualitatively explain, without performing any numerical calculation, why the total mechanical energy of the block decreases during the motion and identify what happens to the energy that is "lost" from the mechanical energy account.
(iv) Briefly describe one experimental method you could use in the school laboratory to verify that the mechanical energy change for the block equals the work done by friction.