Question

What is the mass of a bus moving at a velocity of 110 kph if it has to fully stop before an intersection if a 7000-N of force is applied on it in 15 seconds? *

Answer 1

Given:

$\Delta v=110\:\rm kph=30.6\: m/s$

$F=7000\:\rm N$

$\Delta t=15\:\rm s$

The Newton's second law says

$$F=\frac{m\Delta v}{\Delta t}$$

Hence, the mass of a bus

$$m=\frac{F\Delta t}{\Delta v}=\frac{7000*15}{30.6}=3436\:\rm kg$$