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A ball with a mass of #4 kg# moving at #7 m/s# hits a still ball with a mass of #8 kg#. If the first ball stops moving, how fast is the second ball moving?

Answer 1

Lily Adams

I found: #3.5m/s#

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Answer 2

Charlotte Aaron

To find the velocity of the second ball after the collision, you can use the principle of conservation of momentum. According to this principle, the total momentum before the collision is equal to the total momentum after the collision.

Momentum before collision = Momentum after collision

(mass1 * velocity1)before + (mass2 * velocity2)before = (mass1 * velocity1)after + (mass2 * velocity2)after

(4 kg * 7 m/s) + (8 kg * 0 m/s) = (4 kg * 0 m/s) + (8 kg * velocity2)after

28 kg m/s = 8 kg * velocity2)after

velocity2)after = 28 kg m/s / 8 kg

velocity2)after = 3.5 m/s

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.