A snowboard pulled up by a tow rope travels at the rate of 5 m/s up a mountain. If 3000 watt of power is used, what force was applied to it ?
- A.50 N
- B.100 N
- C.600 N
- D.15000 N
Correct answer
Explanation
The correct answer is C, 600 N. Power equals force times velocity, so the force is 3,000 W divided by 5 m/s, which is 600 N.
Power is the rate of doing work: P = W/t. Work is force times distance, W = F × d, so P = F × d/t, and since d/t is the velocity, P = F × v. Rearranging gives F = P/v = 3,000 ÷ 5 = 600 newtons. The unit check confirms it: one watt is one joule per second, or one newton-metre per second, so watts divided by metres per second leaves newtons. The watt is named after James Watt, and one horsepower is about 746 W.
A is wrong: 50 N would give only 250 W at 5 m/s.
B is wrong: 100 N at 5 m/s is just 500 W, far less than the 3,000 W used.
D is wrong: 15,000 N comes from multiplying power by velocity instead of dividing.
Exam tip: P = F × v, so F = P/v; for a steady pull, power in watts ÷ speed in m/s = force in newtons.
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