Ball dropped from building - find speed and kinetic energy

[NewJersey]

An 0.50kg mass is droped from the top of a 20m tall building. Immediately before hitting the sidewalk

a) the speed of the ball is ?
b) The KE of the ball half way down will be


Help??

 

[hotcommodity]

What's being conserved here, and what equation should you use? Any thoughts?

 

[NewJersey]

Basically right now I am at this point
vf= (2*9.8* 20) the sqaure root of this answer .

Would that tell me the final speed

 

[hotcommodity]

Yes, that is correct.

 

[NewJersey]

So for part b

vf= 2*9.8*10 and the sqaure root of this
= 14

Is this part right.

 

[hotcommodity]

Well, that is the speed that you would plug into the equation for kinetic energy, but yes, you are correct.