Hess Truck vs Wall

Hess Truck Vs Wall
By: Christian Fay




In this experiment, I used one of my hess truck from my 4th grade hess truck phase to show momentum in an elastic collision.  The moving Hess Truck hits the stationary wall at speed and bounces off.  The wall does not move.


Here is the set up, the remote is 8 inches long  (.2 m)

The truck hits the wall with a velocity of 0.44 m/s.
Its final velocity after hitting the wall is  is 0.34 m/s in the opposite direction.
The truck weighs 4.4  KJ



The truck rolls, decelerates a little and then hits the wall at .44 m/s.  After hitting the wall, shown by where the - velocities become positive, the truck reaches .34 m/s and then again decelerates.  The truck has similar velocity in the V1 and V2.  This shows that momentum is conserved.  Being that a plastic truck hits a wooden part of the wall, some energy is lost in the wood and the compression of the plastic bumper and body of the vehicle.  Nevertheless, the truck keeps most of its energy and by keeping a similar velocity it proves that momentum is conserved in collisions.

m1v1=m1v1f+m2v2f
(4.4)(0.44)=(4.4)(0.34)(?)(0)

Since the wall does not move at all, this means that all force exerted by the truck is forced back at the truck.  This is why the velocities are so similar.

Truck before                Truck After                         Wall
KE=1/2mv^2               KE=1/2mv^2                  Stationary
KE=.425 J                    KE= 0.254 J

KE lost =0.17 J

This is due to plastic compressing and the wood being a fairly soft, energy absorbing surface.