Originally Posted by **studiot** Where are you having trouble?
In both these questions you have to calculate the work done.
Do you know how to do this?
Then use work done = energy change.
The answer to question 1 is C and to question 2 is B, what do you think? |

Thanks a lot - I got the same answers as well.

What confused me was:

for Q1:

I used EP (i.e. potential energy) = mass x g x height

and then Average Power = EP/t

I assume this is correct?

I wasn't sure if EP/t is the AVERAGE power...

For Q2:

The height of the archer (or rather the height from which the arrow is released) is not mentioned, not allowing me to calculate the additional energy stemming from the potential energy (mass x g x height) that can be converted into kinetic once the arrow leaves the bow, adding to the total.

So the answer should really be:

Max Poss Kinteic Energy = (F x distance) + (mass x g x height)

and not just F x distance...