Homework Help: physics

Posted by Melissa on Friday, June 15, 2012 at 7:42pm.

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

physics - Damon, Friday, June 15, 2012 at 9:14pm
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

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