LogFAQs > #896391980

one thing I don't like about the question is the phrasing "For the time interval where the two carts are in contact". an instant in time is not really an interval; delta-t would be zero. I guess the interval must be from before there was collision to immediately after the collision?

the more I think of it, the more it makes sense that whatever the first two numbers are, they must be the same. impulse is like accumulating force. it's going to be a vector in the same direction as the force, just a question of magnitude. (think of a space vehicle in orbit. apply thrust, that is your force. the impulse is the accumulation of that force in the direction(s) that it is applied.)

for the magnitude of the impulse... it seems like it might be double or half. I'm a bit confused now by the phrasing "impulse of" VS "impulse on".

I'm not sure of the formulas and wording, but I think that cart 1 has (or applies) twice the force of cart 2. cart 1 receives half the force that cart 2 receives. (call velocity 1 unit, then force is 500 and 250 or something like that.) they are affected for the same duration, so cart 2 will have its momentum modified by twice what cart 1's momentum is modified by. my intuition is that cart 1's velocity would be halved (-250 units), whereas cart 2's velocity would be reversed (-500 units).

am now reading about Newton's third law... seems to say that really they both get the sum of the forces or something, so in that case, it would be 750 units each? or whatever the value is, they'd have the same force applied, their own reversed at them, plus the other's. "impulse of" VS "impulse on" wouldn't matter, they both had the same force applied, and their momentums would have undergone similar modifications (just opposite directions). that feels counter-intuitive though. a semi-truck hitting a motor-cycle doesn't have its own force reflected back at it...
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