Hi,

Hopefully someone can help me understand the following problem.

So, according the Newton's third law we now that for every action there is an equal and opposite reaction.

Let's look at three scenarios. We'll have four marbles, all the same size, but different masses.

Marbles A and B: both 20g

Marble C: 2g

Marble D: 2000g

Speed X: 10cm/s

Scenario #1: (Using Marble A and B)

Marble A rolls at speed X towards Marble B that is at rest. Marble A hits Marble B. This causes Marble A to stop moving and Marble B to move at speed X.

Scenario #1: (Using Marble A and B)

Marble A rolls at speed X towards Marble C that is at rest. Marble A hits Marble C. This causes Marble A to slow down and Marble B to move fast (more than speed X).

Scenario #1: (Using Marble A and B)

Marble A rolls at speed X towards Marble D that is at rest. Marble A hits Marble D. This causes Marble A to bounce back and Marble B to hardly move.

What I don't understand is that in all three scenarios Marble A hit Marbles B, C and D with the same force. I understand why Marbles B, C and D react differently (because of their different masses). What I don't understand is why Marble A behaves differently: either stopping, slowing down or bouncing back. According the Newton's third law, since it hits the three marbles with the same force, the opposite force on Marble A is the same in all three situations. I understand that momentum is conserved, but I would like to deal with the forces issue only. Basically, why does Marble A behave differently to the same reaction force. The behavior of the marbles that it hits seems to influence its own behavior.

Any thoughts would be appreciated,

Shar