Question

A 75 kg bobsled is pushed along a horizontal surface by two athletes. After the bobsled pushed a distance of 4.5 m starting from rest, its speed is 6.0 m/s. What is the magnitude of the net force on the bobsled?

Answer 1

F= 300 N

Explanation:

from the equations of movement:
`v= a xx t`
from which
`t= v/a`
and
`s = s° + v° xx t + 1/2 a xx t^2`
since s° = 0 and v° = 0
`s = 1/2 a xx (v/a)^2`
`s = 1/2 xx v^2/a`
`a = 1/2 xx v^2/s=1/2 xx (6m/s)^2/(4.5 m)=4 m/s^2`
from second dynamic principle
`F= m xx a= 75 kg xx 4 m/s^2= 300 N`