Question

A hockey referee drops a 175 g hockey puck from rest vertically downward from a height of 1.05 m above the ice surface.

(a) Determine the gravitational potential energy of the ju puck relative to the ice before the referee drops it.
(b) Calculate the change in gravitational potential energy of the puck as it drops from the referee's hand to the ice surface.
(c) Calculate the work done on the puck by gravity as the puck travels from the referee's hand to the ice surface.

Answer 1

The gravitational potential energy of a 175 g hockey puck at a height of 1.05 m above the ice is 1.80625 Joules. As it falls, it loses this amount of energy, resulting in a change in GPE of -1.80625 Joules. The work done by gravity on the puck during its fall is also -1.80625 Joules.

Step-by-step explanation:

To calculate the gravitational potential energy (GPE) of the hockey puck, we use the formula GPE = mgh, where m is the mass of the puck in kilograms, g is the acceleration due to gravity (approximately 9.8 m/s2), and h is the height above the ground in meters.

(a) To find the GPE of a 175 g hockey puck at a height of 1.05 m above the ice, we first convert the mass to kilograms (175 g = 0.175 kg) and then calculate: GPE = 0.175 kg * 9.8 m/s2 * 1.05 m = 1.80625 Joules.

(b) The change in gravitational potential energy as the puck drops is equal to the initial GPE, since it will be zero when it hits the ice, hence the change is -1.80625 Joules (negative because it's losing GPE).

(c) The work done by gravity on the puck is equal to the change in GPE, which is also -1.80625 Joules.