In a crash test the strapped-in, 75-kg dummy moves a distance of 0.80 m when the test car is slammed straight into a wall at 11.2 m/s (~25 mph). the average force acting on the dummy during the collision is how many times his own weight?

Explanation:

It is given that,

Mass of the dummy, m = 75 kg

Distance, d = 0.8 m

Initial speed of the dummy, u = 0

Final speed of the dummy, v = 11.2 m/s

Firstly finding the acceleration of the test car. Using third equation of motion to find it as :

Let F is the average force. It is given by the product of mass and acceleration. It is given by :

F = 5880 N

Taking ratios,

The average force acting on the dummy during the collision is 8 times of his weight. Hence, this is the required solution.