physics
posted by Melissa .
Some children go tobogganing on an icy hill. The start from the rest at the top of the hill. The toboggan and children have a combined mass of 94 kg. The height of the first hill a is 12.0m the height of b is 0, and the height of c is 3.0m. If friction is small enough to be ignored , apply the law of conservation of energy to determine
A) the total mechanical energy of the toboggan at a relative to b
B) the sped of the toboggan at b
C) the speed of the toboggan at c

E = (1/2) m v^2 + m g h = constant forever in this problem
mass does not matter here, cancels
E = m g (12) forever
m g (12) = (1/2) m v^2 + m g(0) at b
12 * 9.8 = (1/2) v^2 solve for v at b
m g (12) = (1/2) m v^2 + m g (3)
9 * 9.8 = (1/2) m v^2 solve for v at c