ASSUME : For all parts of this question, friction is negligible. A helicopter is
ID: 2177427 • Letter: A
Question
ASSUME: For all parts of this question, friction is negligible.
A helicopter is used to lift an astronaut of mass m = 71.5 kg a distance s = 18.8 m vertically out of the ocean by means of a cable. The astronaut rises with constant upward acceleration of magnitude a = 8.18 m/s2 until she reaches the helicopter.
a) Find Wh, the work done by the helicopter on the astronaut.
1 J
b) Find Wg, the work done by gravity on the astronaut.
2 J
c) If the astronaut started from rest, find the speed v with which she reaches the helicopter.
3 m/s
d) Find Pavg, the average rate at which work was done by the helicopter to lift the astronaut.
4 W
e) Find Pinst, the instantaneous rate at which work was being done by the helicopter at the instant the astronaut reaches the helicopter.
5 W
Explanation / Answer
a)
force applied by helicop = F=m*(g+a)=1285.57N
W=F*S
=24168.716J
b)
mgS = 13173.16J
c)
V=(2*a*S) =17.53m/s
d)
t=V/a=2.14s
P=W/t =11272.91W
e)
F*V = 22536.04W