PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A teacher drops a cup of coffee from a height of 1.5m. The mass of the cup of coffee is 0.45kg. Ignore air resistance.
(a) Calculate the work done by Earth's gravitational field on the cup of coffee.
(b) Without referring to the principle of conservation of energy, show that the kinetic energy of the cup of coffee just before it hits the ground equals the work done by Earth's gravitational field on the cup of coffee.
(c) Verify that the gravitational potential energy lost by the cup of coffee is transferred into kinetic energy.
(d) When the cup of coffee hits the floor, it breaks and the pieces of the cup eventually stop moving. With reference to the principle of conservation of energy, suggest what has happened to the gravitational potential energy that the cup once had.