# ap physics

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A skier of mass 70.5 kg is pulled up a slope by a motor-driven cable. How much work is required to pull the skier 60 m up a 38° slope (assumed to be frictionless) at a constant speed of 2.0 m/s?

• ap physics -

The elevation gain is
H = 60 sin38 = 36.9 m

The energy required is the potential energy gain,
E = M g H

The speed does not matter, as long as it is constant. Kinetic energy stays the same.

• ap physics -

25521 J

• ap physics -

work=20,580J
power=686 watts

• ap physics -

18081 J

• ap physics -

A skier of mass 61.0 kg is pulled up a slope by a motor-driven cable. (a) How much work is required to pull him 40.0 m up a 30.0° slope (assumed frictionless) at a constant speed of 4.00 m/s? (b) What power must a motor have to perform this task?

• ap physics -

skier of mass 79 kg is pulled up a slope by a motor-driven cable.
(a) How much work is required to pull him 80 m up a 30° slope (assumed frictionless) at a constant speed of 3.4 m/s?
1 J

(b) What power (expressed in hp) must a motor have to perform this task?