Second time asking this question please only answer if you are certain A helicop

Question

Second time asking this question please only answer if you are certain

A helicopter lifts a 70.0 kg astronaut 29.0 m vertically from the ocean by means of a cable. The acceleration of the astronaut is upward and has a magnitude of g/10.

(a) Does the mechanical energy of the astronaut-Earth system increase, decrease, or remain the same as the astronaut is lifted?

Increase Decrease     X Remain the same ***incorrect

(b) How much work is done on the astronaut by the force from the helicopter?
21883.45 J

(c) What is the change in potential energy of the astronaut-Earth system?
19894 J

(d) What is the kinetic energy of the astronaut just before she reaches the helicopter?
-2103 J

(e) What is the speed of the astronaut just before she reaches the helicopter?
7.75    m/s***incorrect

Explanation / Answer

a] increases,

because both the KE and PE increases.

b] Work = Fs = Mg*11/10 *h = 70*9.8*1.1*29 = 21883.4 J

C] PE = mgh = 70*9.8*29 = 19894 J

e] v = sqrt(2as) = sqrt(2*0.1*9.8*29) = 7.539 m/s

d] KE = 0.5mv^2 = 0.5*70*7.539^2 = 1989 J

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