Question

A hockey puck with a mass of 0.175 kg slides over the ice. The puck initially slides with a speed of 5.25 m/s, but it comes to a rough patch in the ice which slows it down to a speed of 2.85 m/s. How much energy is dissipated as the puck slides over the rough patch?

Answer 1

1.70 J

Step-by-step explanation:

The heat dissipated is the difference in the kinetic energies.

This is given by

`E = (1)/(2)mv_f^2 - (1)/(2)mv_i^2`

`v_i` and
`v_f` are the initial and final velocities.

With m = 0.175 kg,

`E = (1)/(2)*0.175(2.85^2 - 5.25^2) = -1.701\text{ J}`

The negative sign appears because energy is lost.