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# help with physics?

A 0.150 kg projectile is fired with a velocity of +745 m/s at a 2.00 kg wooden block that rests on a frictionless table. The velocity of the block, immediately after the projectile passes through it, is +45.0 m/s. Find the velocity with which the projectile exits from the block.

_________ m/s

### 2 Answers

- 1 decade agoFavorite Answer
First you need to find the energy of the projectile. Then you need to know the amount of energy that would be needed to accelorate the block to that speed. Once you have the two you will be able to know the energy of the projectile after it exits the block/ if it does. Then with the energy of the projectile you will be able to find the speed of the projectile.

I would like to tell you, but just being told will never help you pass the test, i should know.

- 1 decade ago
OK, momentum is conserved, right? Calculate the momentum of the projectile, calculate the momentum of the block (after it is struck), calculate the difference between the two. Re-calculate the velocity of the projectile based on the new momentum. That should work. . . provided I am not getting my physic's principles all mixed up.