00:02
Hello, so here we got some, you know, you got a bullet, let's say, oh, here, coming that way and then there is a block here.
00:15
So it's going to collide with the block and then after collision, we're going to have something like this.
00:23
So you're going to have the bullet stick to the block and then it's going to travel a distance 0 .31 meters.
00:33
At the end of the journey the velocity here is zero so we're trying to find the initial velocity of the bullet here you so what we need to do first is to look at this part of the motion which is going to be after collision what's going on here after collision because i'm trying to get the initial velocity of the mouse and the bullet okay before they travel that distance of 0 .31 so i'm trying to find this velocity here in v.
01:08
If i find it, i can use conservation of momentum to get the initial speed of the bullet alone.
01:15
So what is going on here is that this bullet and the block is going to travel that distance because the final velocity is zero.
01:23
That something is taking away the kinetic energy.
01:27
And that's going to be the friction.
01:30
So we're going to do energy conservation and say that the change in kinetic energy is going to be called to the work done by the friction.
01:40
So let's look at work done by friction.
01:44
That's going to be the fractional force times the distance traveled.
01:49
Frictional force is mule n times d.
01:56
So in this case, let me use a different color here.
02:01
Our n is going to be that way.
02:04
And here is going to be the weight.
02:05
So our weight is going to be the total mass of the bullet and the block times gravity.
02:14
So you're going to have mxm xmx n which is m plus m g times d.
02:27
So now let's see.
02:28
So you have half.
02:30
Now m here too is going to be the total mass.
02:34
That's kinetic energy v squared because mu.
02:38
M plus m...