Question

A father pushes his young daughter on a sled up a 15o inclined-plane which is moving at a

constant velocity. If the push of the father is directed horizontally with a magnitude of

92.0 N, (a) how much work is done by the applied force of the father on the sled with the girl

up to a height of 3.25 m from the base of the inclined plane? (b) What is the work done by

the weight on the sled with the girl if its total mass is 35.0 kg?

Answer 1

Given:

$\theta=15^\circ$

$F=92.0\rm \: N$

$h=3.25\:\rm m$

$m=35.0\:\rm kg$

(a) the work done by the applied force

$$W_1=Fd=Fh/\sin\theta\\ =\rm 92.0*3.25/\sin15^\circ=1155\: J$$

(b) the work done by the gravity force

$$W_2=mgh\\ =35.0*9.8*3.25=1115\:\rm J$$