Question

A vehicle of mass $120kg$ is moving with a uniform velocity of $90km{h}^{-1}$. Find the value of the force required to stop the vehicle in $10$ seconds.

Answer 1

Given mass of the vehicle(m)=120 kg and initial velocity u= 90 km/h

u$=90km/h=90\times \left(\frac{5}{18}\right)=\text{25 m/s}$

As the vehicle is needed to be stopped in 10 seconds the final velocity will be =0 m/s.

We know acceleration$=\frac{Final-initialvelocity}{time}$

$=\frac{0-25}{10}=-2.5m/s^2$

And also Force= mass$\times$acceleration

$=120\times (-2.5)=-300N$

{The negative sign implies that the force is applied in the direction opposite to that of the direction of motion}