00:01
Here we have a bullet shot with a velocity v equals to 320 meters per second, and whose mass is equal to 25 grams, or 0 .025 kilograms.
00:17
It eventually hits a block of mass m equals to 22 kilograms, and that which is suspended from a string of length l equal to 1 .25.
00:43
So eventually it will raise a height h and there will be an angle that the string makes with the vertical.
00:57
So we want to know what that angle is.
01:00
The first thing we can do this with conservation of energy and momentum.
01:05
Using momentum, we know that initial momentum must be equal to final momentum.
01:11
Thus, we want to know the velocity of the block -mat bullet system right when the bullet hits and sticks to the mass.
01:21
P -initial should just be the mass of the bullet times the velocity of the bullet, which will be equal to the final momentum, which should be the mass of the block.
01:37
Plus the mass of the bullet times the final v that we want.
01:44
Thus, that v will be mb, vb, over m plus m mass of the bullet.
01:57
Now, with conservation of energy, this will tell us how high the bullet goes, or how high the whole system goes.
02:06
This should be gravitational potential energy, will be the final form, of energy, and this tells you the height that this block has gone, which should be equal to one -half mv squared...