00:01
So this question asks us about two different ballistic pendulum experiments.
00:09
So ballistic pendulum, this question does not explain very detailedly what is happening in a ballistic pendulum.
00:18
But example 7 .9 has a very detailed walkthrough of this setup.
00:26
So make sure you check example 79.
00:29
Line.
00:30
But just to do a quick recap of what's happening.
00:34
In a ballistic pendulum, you have a pendulum that has a mass of big m.
00:41
And then you have a bullet that has a mass of small m and velocity.
00:46
It hits the block.
00:49
It's embedded into the block.
00:51
And its momentum makes the whole pendulum going up a little bit to a height of age.
01:00
So there are two things that's happening here.
01:03
The first is the conservation of momentum.
01:05
So the initial momentum and v eventually becomes big m plus n and v part because it's in the elastic collision as a bullet is embedded into the block.
01:15
So the velocity after it hits the block, the velocity of both the block and the bullet is small n v over big m plus small m.
01:26
Or see as a way, small v equals big m plus plus and over small m times b prime so that's step one and step two is that afterwards after it has the velocity b prime this whole thing rise up to a height of age and that is the conservation of kinetic energy and potential energy so what happens is that the initial kinetic energy assuming this point has no gravitational potential the initial kinetic energy are all transferred into gravitational potential energy.
02:07
So that gives us v -prime square equals 2gh, or v -prime equals square root of tgh...