Question

A 5000 KG TRUCK IS RUNNING AT 72 KPH.

a. ) IF IT IS TO BE STOPPED BY A CONSTANT RETARDING FORCE IN 10 S. WHAT IS THE DECELERATION ?

b ) WHAT IS THE RETARDING FORCE ?

Answer 1

Given:

$m=\rm 5000\: kg$

$v_i=\rm 20\: m/s$

$v_f=\rm 0\: m/s$

$\Delta t=\rm 10\: s$

(a) the deceleration of the truck

$$a=\frac{\Delta v}{\Delta t}=\frac{-20}{10}=\rm -2\: m/s^2$$

(b) the retarding force

$$F=ma=5000*2=10000\:\rm N$$