Question

A truck of mass $2000kg$ travelling at $4\text{m/s}$ comes to rest in $2\text{s}$ when it strikes a wall. Force exerted by the wall is

• A. $2kN$
• B. $1kN$
• C. $4kN$
• D. $8kN$

Answer 1

The correct option is C $4kN$

Given:
Mass of truck; $m=2\times {10}^3\text{kg}$
time; $t=2\text{s}$
Initial velocity of truck; $v_i=4\text{m/s}$
As truck comes to rest.
$\therefore$Final velocity of truck; $v_f=0\text{m/s}$
We know,
Impulse $\left(J\right)=Ft=\Delta P$
$Ft=m(v_f-v_i)$
$F\left(2\right)=2\times {10}^3(0-(-4\left)\right)$
$2F=8\times {10}^3$
$F=4\times {10}^{3}N=4kN$