Question

In the winter sport of curling, players give a 20 kg stone a push across a sheet of ice. A curler accelerates a stone to a speed of 3.0 m/s over a time of 2.0 s.

a. How much force does the curler exert on the stone?

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b. What average power does the curler use to bring the stone up to speed?

Answer 1

PREPARE: Both the parts of this question involve simple and direct substitution into standard equations.

SOLVE:

Given m = 20 kg, v = 3.0 m/s, t = 2.0s

(a)Force exerted by the curler on the stone is the normal force F = ma

a = = =

Thus, applied force F = (20 kg) ( )

F = 30 N

(b)Power is given as, P =

And work done, W = F d

Let’s use the kinematic equation to find the distance d

d = 3 m

Thus, work done, W = F d

W = (30 N) (3 m)

W = 90 J

Thus power, P = =

P = 45 W

ASSESS: Once again we had a simple and straight forward question. These are aimed at strengthening our basics and not for testing them.