Which battery will last the longest Superlast or energy star? IV: DV: CV:
2 answers:
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Apply the law of conservation of momentum for this situation. The law states that the momentum of a system is constant (in absence of external forces acting on it).
The 'system' in this case are the two skaters. There is no external force on the skaters. Suppose the skaters are initially standing still. The momentum in the system is 0. This value will need to remain constant, even after the mutual push (which is a set of forces from <em>inside</em> the system). So we know that
(total momentum before) = (total momentum after)
Indexing the masses and velocities by the first letter of the skaters' names:
From the last row, you can see that the skaters will have momentum of same magnitude but opposite direction, after the push off. That answers the first question: neither will have a greater momentum (both will have one of same magnitude).
Since Ricardo is heavier, from the above equality it follows that
In words, Paula has the greater speed, after the push-off.