A wagon is coasting along a level sidewalk at \(5.00 \mathrm{~m} / \mathrm{s}\). Its wheels have very good bearings. You are standing on a low wall, and you drop vertically into the wagon as it passes by. The wagon has an inertia of \(100 \mathrm{~kg}\), and your inertia is \(50.0 \mathrm{~kg}\).

(a) Use conservation of momentum to determine the speed of the wagon after you are in it.

(b) Use conservation of energy to determine that speed.

(c) After comparing your answers in parts \(a\) and \(b\), explain which method is correct.