Question #918

A boy,pulls a 1.0 kg toy horizontally in a straight line at a constant speed of 20 m/min by exerting a 3.0 N force at an angle of 30 degrees with the horizontal.What is the average power developed by the boy?

Expert's answer

The average power will be equal to the total work (F*S, there F is the force, S - is the path) per some time (t):

W = (F*S)/t = F * V (v - speed);

As the force exerts at the angle to the horizont, we have to take its projectile:

F = F' cos (30) = 3 * 0.867 = 2.6

20 m/min = 20/60 = 0.33 m/sec.

W = 2.6 * 0.33 = 0.86 [W].

W = (F*S)/t = F * V (v - speed);

As the force exerts at the angle to the horizont, we have to take its projectile:

F = F' cos (30) = 3 * 0.867 = 2.6

20 m/min = 20/60 = 0.33 m/sec.

W = 2.6 * 0.33 = 0.86 [W].

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