# Homework Help: Collision between 2 cars

1. Oct 6, 2011

### gamepro9

Amy was traveling East with Perodua Myvi 1.3 when she entered the fateful intersection. When she reached the center of the intersection, her car was struck by the other car, Honda Insight which was traveling South. Her car skidded 15m and the Honda Insight skidded 30m after the collision. The speed limit on both roads is 60km/h
Prove that she was under the speed limit

I could not find enough info from this question to calculate. Can anyone help?

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2. Oct 6, 2011

### Staff: Mentor

What equations do you know that might be applicable to this?

3. Oct 6, 2011

### gamepro9

M1U1+M2U2=M1V1+M2V2
i think is related to this formula

4. Oct 7, 2011

### Staff: Mentor

I'm coming to the conclusion that we have to make some unreasonable assumptions, in order to arrive at an answer.

Had we been asked to prove that she was speeding, I'd have offered the evidence that her car moved the house back 10 metres!

The fact that the car from the north seems to have been involved in two collisions may be a clue, on the other hand, it may be a red herring. Maybe it just clipped a power pole? Though if the vehicles do collide for a second time, the force of collision deflects their paths in exactly the wrong directions!

The collision transferred to the east-travelling car an amount of momentum equal to that with which it had before the collision. But an equal loss of momentum by the car from the north seems to not have slowed its southward progression by nearly as much, implying that it had lots more momentum to begin with. The eastwards momentum that was transferred to the car from the north deflected its travel only slightly in comparison with its southward travel.

Their paths actually cross again after the collision, too. Mysteriously. Maybe there's a clue there. Obviously, the car with greatest speed got to the point where paths intersect ahead of the later car.

I'm not going to be able to solve this on my own!

Last edited: Oct 7, 2011
5. Oct 9, 2011

### gamepro9

Thanks for your reply..erm i think this collision is inelastic.. the thing you saying is for elastic if i m not mistaken.. look at the picture.

6. Oct 9, 2011

### Staff: Mentor

Transfer of momentum is independent of elastic or inelastic collision. By "looking at the picture" I can make no deduction regarding elastic or inelastic (except in the obvious case where the two vehicles become fused together).