Question

A cart of mass $20kg$ at rest is to be dragged at a speed of $18km{h}^{-1}$. If the co-efficient of friction between the cart and the ground is $0.1$, what is the minimum force required to drag the cart to a distance of $10m$? (Take $g=10m{s}^{-2})$.

Answer 1

$speed=18km/hr$

$=5m/s$

So initial $KE=\frac{1}{2}m{V}^2$

$=\frac{1}{2}\times 20\times 25$

$=250Joules$

$f=fs$ for constant speed

$f\left(10\right)-f\left(s\right)=250$

$f\left(10\right)-Nu10=250$

$10f-420g10=250$

$10f-20\times 10\times 10\times 0.1=250$

$10f=250+200$

$f=45newtons$.