Falling egg question (with energy equations)

[jackamo321]

An egg of mass 5.8*10^-2 is dropped from a height of 1.5m onto a floor. Assuming air resistance is negligable, calculate for the egg:

a) loss of potential energy.
b) the kinetic enrgy just before impact.
c) the speed just before impact
d) the momentum just before impact.

So far i have done the potential energy one, and now I am stuck on the others. As the equation for KE is KE=1/2mV^2 but we do not know the velocity. And i cannot find out the velocity because we don't have the time either. So i was just wondering how i would work out b-d as all of their equations require velocity.

Thanks

Jack

 

[horatio89]

An egg of mass 5.8*10^-2 is dropped from a height of 1.5m onto a floor. Assuming air resistance is negligable, calculate for the egg:

a) loss of potential energy.
b) the kinetic enrgy just before impact.
c) the speed just before impact
d) the momentum just before impact.

So far i have done the potential energy one, and now I am stuck on the others. As the equation for KE is KE=1/2mV^2 but we do not know the velocity. And i cannot find out the velocity because we don't have the time either. So i was just wondering how i would work out b-d as all of their equations require velocity.

Thanks

Jack

I hope you are familiar with the concept of energy conservation. What happens to all that potential energy lost when it's dropped?

 

[jackamo321]

oh ok, does that mean that the kinetic energy will be the same as the loss of potential energy then? But still, how do i work out the speed and momentum?

 

[horatio89]

Right, you now have KE before impact, and that KE = 1/2mv^2...

 

[jackamo321]

Thanks alot! think I've done it now!

 

[raghu199]

Conservation of Energy is easy. But to clarify, you can still calculate the velocity without it.
The egg has been dropped => initial velocity is zero!
All freely falling bodies accelerate at g which is 9.8m/s2
The body traveled 1.5m before hitting the ground.
You will need two equations and work a little more.