Ahelicopter lifts a 60 kg astronaut 17 m vertically from the ocean by means of a cable. the acceleration of the astronaut is g/10. (a) how much work is done on the astronaut by the force from the helicopter? 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 the helicopter?

Explanation:

mass =60kg d = 17m  a=g/10

(a) work done on the astronaut by the force from the helicopter = fd

but f =m(g+a)

 w= m( g+g/10)d

wt = 11/10 mgd

w =11/10 * 60 *9.8 * 17 = 10995.6J  = 1IKJ

(b) workdone  by her weight = -mgh

   = 60*9.8* 17 = -9996J

(C) Kinetic energy = wt + w

                             = (10995.6 - 9996)J = 999.6J

(d) Kinetic energy =1/2m

hence velocity = = 5.777m/s