Question

A man claims he can safely hold on to a 12 kg child in a head-on collision with a relative speed of 120 mi/h lasting for 0.10s as long as he has his seat belt on.

1. Find the magnitude of the average force needed to hold onto the child.

2. Based on the result to part (a), is the man’s claim valid?

3. What does the answer to this problem say about laws requiring the use of proper safety devices such as seat belts and special toddler seats?

Answer 1

Here we have given that,

Mass of child M = 12 kg

speed Vi = 120 mi/h = 53.6448 m/s

t = 0.10s

So that  the magnitude of the average force needed to hold onto the child will be given as,

I = delta P

Ft = m(Vf-Vi)

Here Vf = 0

So that magnitude of the force will be

F = mVf/t = 12× 53.6448/0.1

F = (6436.8) N

Now for the next part , here The force needed to make the child come to a scope is very high so that the claim of the man to be able to hold on to the child is not valid

Now for the next part,

Here the law that required and say about this problem regarding for proper safty purpose is the impulse-momentum theorem and we can say that passengers have to wear a seat belt when driving inside a car at high speeds.