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# Direction of Impulse? (M1) watch

1. Which way is the magnitude of impulse going if a ball is bouncing off a wall? Is it towards the wall or away from the wall?
2. (Original post by amelienine)
Which way is the magnitude of impulse going if a ball is bouncing off a wall? Is it towards the wall or away from the wall?
It depends on the velocity of the ball, but obviously its towards the wall. Try it with calculations.
3. Impulse is a vector quantity, i.e. it has both magnitude and direction. When a ball bounces off a wall, the impulse imparted on the ball is opposite in direction to the direction of travel of the ball immediately before the impact.

In general, if the impulse imparted on an object is in the same direction as the object is already travelling, the object will speed up without changing direction. On the other hand, if the impulse imparted on an object is opposite in direction to the direction in which the object is already travelling, it will either slow down while continuing in the same direction, or, if the impulse is big enough, it will reverse its direction of travel.
4. (Original post by amelienine)
Which way is the magnitude of impulse going if a ball is bouncing off a wall? Is it towards the wall or away from the wall?
Imulse is proportional to force and time. When a ball hits a wall, the wall "forces" the ball away from the wall so the impulse is directed on the ball away from the wall.

Similarly when ball A hits ball B, ball A forces ball B in the direction that ball A was travelling so the impulse on B by A is in the direction that A was travelling before the impact.

It's quite simple if you think of it in this way.
5. (Original post by Reshyna)
It depends on the velocity of the ball, but obviously its towards the wall. Try it with calculations.
Assuming the OP means the impulse on the ball, the impulse will be directed away from the wall.
6. (Original post by notnek)
Imulse is proportional to force and time. When a ball hits a wall, the wall "forces" the ball away from the wall so the impulse is directed on the ball away from the wall.

Similarly when ball A hits ball B, ball A forces ball B in the direction that ball A was travelling so the impulse on B by A is in the direction that A was travelling before the impact.

It's quite simple if you think of it in this way.
Thank you! Makes sense now

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