00:01
In this problem, we have a collar that's being pulled through a cord with a force of 300 newtons.
00:07
We're also given the mass of this collar, which is 15 kilograms.
00:12
You want to find the velocity, which we'll call v2, when it reaches point b of the cord.
00:20
Well, since you're dealing with forces and we want to find the velocity, we can use the work energy principle.
00:33
Which is given as the initial kinetic energy plus the work being done by the forces is equal to the final kinetic energy.
00:43
Because this collar is initially at rest, then the initial kinetic energy is zero, its velocity is zero.
00:52
So we're just left with the work being done by the forces is equal to the final kinetic energy, one half, the mass of the of the collar.
01:05
Times the velocity 2 squared and this is what we're trying to solve now let's look at the work being done by the forces we know that work is equal to force times distance and here the force is constant so we have force times some distance that the collar travels but we also have the force due to the weight of the collar and that's in the opposite direction of the force that's pulling it up because the weight is trying to pull it back down.
01:40
So the work is negative...