Question

In a crash test, a truck with mass 2500 kg traveling at 24 m/s smashes head-on into a concrete wall without rebounding. The front end crumples so much that the truck is 0.72 m shorter than before.
a. What is the average speed of the truck during the collision (that is, during the interval between first contact with the wall and coming to a stop?
b. About how long does the collision last?
c. What is the magnitude of the average force exerted by the wall on the truck during the collision?

Answer 1

Answer:

Explanation:

Given

mass of truck $m=2500\ kg$

velocity of truck $u=24\ m/s$

Crumbled distance $d=0.72\ m$

using equation of motion

$v^2-u^2=2as$

where u=initial speed

v=final speed

a=acceleration

s=displacement

$0-(24)^2=2\times (a)\times (0.72)$

$a=-400\ m/s^2$

(b)using $v=u+at$

here $v=0$

$-u=-400\times t$

$t=\frac{24}{400}=0.06\ s$

Impulse imparted is    $J=F_{avg}\times \Delta t=\Delta P$

$F_{avg}=\frac{2500\times 24}{0.06}$

$F_{avg}=1000\ kN$