posted by Andrea .
Consider a roller coster car moving along a track from point A to point B to point C. a)if the roller coaster car starts from rest at point A (30m above the bottom of a dip (point b). What would be the speed of the car at the top of the next hill (point C), which is 20 m above the bottomm of the dip. Assume friction is negligible.
My issue is whether h is actually 20m (the distance b/w B and C)or is it 10m(the distance b/w A and C)
b) if instead the roller coaster car started with a speed of 20m/s at point A what is its speed at the top of the next hill (point C) Assume friction is negligible.
is this correct?
a) You got the right answer,but I would have worked it different, which answers your issue:
Total energy remains constant.
final energy= initial energy
PEfinal+KEfinal = PE initial + KE initial
mg20 + 1/2 mvf^2 = mg30 + 0
b) you did it wrong. Do it the way I outlined in a), you now have an initial KE.