UPSB v4
Spammer's Bin / physics help
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Date: Wed, Jan 19 2011 01:05:06
@strat or anyone who can help me a 7g bullet is fired into a 1.5 ballistic pendulum. The bullet emerges from the block with a speed of 200 m/s, and the block rises to a maximum vertical heigt of 12 cm find 1.Vi immidiatly after the collision 2.Vi before the collision 3.KE lost thx
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Date: Wed, Jan 19 2011 01:05:33
@strat1227
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Date: Wed, Jan 19 2011 01:22:08
these are fun problems because they mix conservation of energy and momentum collisions don't conserve energy, you have to do it in 2 parts, before and after the collision at the end you have Ke of the bullet (1/2)mv^2 and Ue of the block mgh add those together and you have total energy after the collision this amount of energy is the same as the energy RIGHT after the collision (aka when the bullet hits) at that point you only have Ke (1/2)mv^2 (this m and v are for bullet+block combination, make sure you add the masses) and then from that you can use momentum conservation to determine how fast the bullet was traveling (I explained the problem instead of actually doing it for you, let me know if you have any questions) @mintypaladin