Head Fall Acceleration Question

[diesel828]

Hello,
I'm not particularly looking for the answers in this problem as much as I am looking for the method to the solution. It's been giving me a headache.

1. Traumatic brain injury such as concussion results when the head undergoes a very large acceleration. Generally, an acceleration less than 800 m/s^2 lasting for any length of time will not cause injury, whereas an acceleration greater than 1,000 m/s^2 lasting for at least 1 ms will cause injury. Suppose a small child rolls off a bed that is 0.40 m above the floor. If the floor is hardwood, the child's head is brought to rest in approsimately 2.0mm. If the floor is carpeted, this stopping distance is increased to about 1.0 cm. Calculate the magnitude and the duration of the deceleration in both cases to determine risk of injury.

Thanks for any advice.

 

[Hootenanny]

One is suppose to show ones efforts before asking for help...

 

[diesel828]

Oh. Well, I took my best stab at it and turned it in. I'm going to wait and see how I did. The problem really gave me a headache for some reason. Similar questions weren't so bad. Maybe it was the image of a baby falling off a bed? I don't know.
I'll post my results.

 

[radou]

Traumatic injuries? Small children rolling off their beds? This is the third or fourth time someone posts such interesting mechanical problems.