Question

A person having a mass of 60 kilograms exerts a horizontal force of 200 newtons in pushing a 90-kilogram object a distance of 6 meters along a horizontal floor. He does this at constant velocity in 3 seconds.The force of friction is

Answer 1

First find the acceleration

$u=0m/s$

$s=ut+1/2at^{2}$

$6=1/2\times a\times 3^{2}=9a/2$

$a=6\times 2/9=4/3 ms^{-2}$

$F=ma=90\times 4/3=120N$

The force of friction $=200N-120N=80N$