(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A 0.5 kg object drops from rest from a 3m high point. On bouncing from Earth it rises to a height of 2m. The collision with Earth lasts for about 10^-4 seconds.

i) What is the impulse received by the object?

ii)Considering that there is a gravitational force present, Can you assume that in the collision F(ext)=0? If so, what is the change in the Earth's momentum?

iii)Is this collision totally elastic? Justify.

2. Relevant equations

J=F*(delta)t

F=ma

3. The attempt at a solution

i)So, I've got the first part down. Impulse will be the mass*acceleration*change in time. Which is (.5)(9.8)(10^-4) =0.00049

This is where I need help:

ii)I'm not sure if this can be assumed. If there IS a change in the earth's momentum and F(ext)=0, it would just be -0.00049... But I'm unsure about this part. Help?

iii) If this was totally elastic, the ball would return to 3m high, not 2m - right? So this is NOT totally elastic. (Let me know if I'm confused here.)

Thank you in advance for helping me to understand this.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Impulse -

**Physics Forums | Science Articles, Homework Help, Discussion**