A wooden block of mass M is hanging freely in the air from a light string of length l. A bullet, of mass m travelling at a speed v, hits the block and becomes embedded in it. The block then wings upwards.
Which of the following are employed in determining the maximum height reached by the block?
(1) law of conservation of energy
(2) law of conservation of momentum
(3) principle of moments
答案係1,2
我想問max height同momentum有咩關係??
mechanics - energy
2007-05-01 10:02 am
回答 (2)
2007-05-01 10:10 am
✔ 最佳答案
1) law of conservation of energyNot much, only KE = PE
2) law of conservation of momentum
Since the bullets is moving and collide and becomes embedded in it.
mu(bullet) + mu (wooden block) = m(bullet and wooden block) v
You can calculate the KE of the block at that moment and also the PE can be done, and hence the max height can be done also.
3) principle of moments
It had been out of syllabus in fact.
2007-05-01 10:07 am
by the law of consevation of momentum u can get the speed after the bullet embedded in the block hehe
收錄日期: 2021-04-19 22:28:01
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