The Student Room Group
Reply 1
a) Speeds (or more accurately velocities) can be split into components just like forces. If the resultant velocity is 6.5ms-1 down the slope, then you can find the vertical component using: sin 4.5 (that is the fraction of the resultant that is vertical)

b) Using your answer to part a, try thinking about how much P.E is lost per second....well to do that you just need to know how far the child travels vertically PER SECOND. And hey, we have that...it's the answer to part A. So use P.E=mgh....convert that to: Work rate = P.E per sec = mgh per sec = mg * distance per sec = mg * vertical velocity
you have the vertical velocity from the first answer!