A helicopter, starting from rest, accelerates straight up from the roof of a hospital. The lifting force does work in raising the helicopter. An 810-kg helicopter rises from rest to a speed of 7.0 m/s in a time of 3.5 s. During this time it climbs to a height of 8.2 m. What is the average power generated by the lifting force?(adsbygoogle = window.adsbygoogle || []).push({});

M = 810 kg

V_{0}= 0 m/s

V_{f}= 7 m/s

t = 3.5 s

y = 8.2 m

Force acting on helicopter: mg and F_{L}(the lifting force)

It is accelerating upward. Find acceleration, a:

V_{f}= Vo + at

a = (V_{f}- Vo)/t

a = 2 m/s^{2}

F_{L}- mg = ma

F_{L}= mg + ma

F_{L}= 810(9.8+2)

F_{L}= 9558 N

P = F_{L}x avg V = 9558 N x 3.5 m/s

P = 33453 watts?

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# Work, power, acceleration problem

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