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# Car crashes into a barrier, impulse needed to stop the child

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A car moving at 8 m/s crashes into a barrier and stops in 0.050 s. There is a 19 kg child in the car. Assume that the child's velocity is changed by the same amount as the car's in the same time period.

(a) What is the impulse needed to stop the child?
N·s

(b) What is the average force on the child?
N

(c) What is the approximate mass of an object whose weight equals the force in part (b)?
kg

(d) Could you lift such a weight with your arm?
Yes
No

(e) Why is it advisable to use a proper infant restraint rather than hold a child on your lap?

https://brainmass.com/physics/velocity/car-crashes-barrier-impulse-needed-stop-child-282256

#### Solution Preview

a) Initial speed of the car (and the child) = 8 m/s

Final speed of the child = 0

Time taken for the change of speed fom 8 m/s to zero = 0.05 sec

By definition, impulse Fdt = d(mv) [change in ...

#### Solution Summary

The expert examines car crashes into a barriers and the impulses need to step the child.

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