A helicopter lifts a 56 kgastronaut 14 m vertically fromthe ocean by means of a

Question

A helicopter lifts a 56 kgastronaut 14 m vertically fromthe ocean by means of a cable. The acceleration of the astronautis g/10. (a) How much work is done on the astronaut by the force from thehelicopter?
J

(b) How much work is done on the astronaut by her weight?
J

(c)What is the kinetic energy?
J

(d) What is the speed of the astronaut just before she reaches thehelicopter?
m/s
(a) How much work is done on the astronaut by the force from thehelicopter?
J

(b) How much work is done on the astronaut by her weight?
J

(c)What is the kinetic energy?
J

(d) What is the speed of the astronaut just before she reaches thehelicopter?
m/s

Explanation / Answer

(a) Work done W = F*s = ma*s = 56*[ 9.8 + 0.98]*14 = 8451.5J (b) the workdone by weigth   W = F*s = (mg)h =56*9.8*14 = - 7683 J (c) From work enrgy theorem        W = KE so KE = 8451.5J - 7683 J = 768.5 J (d)       From above 1/2mv2 = 768.5     therefore velocity v = 5.23 m/s

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