00:01
In this problem, we have an object sliding on a flat level floor and coming to a stop with an acceleration of 2 .4 meters per second squared.
00:13
This is just the magnitude, we don't know the direction.
00:15
And we want to find the coefficient of kinetic friction.
00:20
And so i'm going to draw a free body diagram of the situation.
00:23
So since it's on a flat ground, we have force of gravity going down, which we know is mass times gravity.
00:29
And we have normal force going upward.
00:33
Since this is on a flat surface and there is no acceleration in the vertical direction, we know that the force in the vertical direction, our force net, must be equal to zero.
00:43
They're going to cancel each other out.
00:44
So that means our force of gravity is equal to normal force, which means normal force is equal to mass times gravity.
00:52
We're going to need this here in a minute, so let me just leave that to the side.
00:55
We know the only horizontal force is the force of friction.
01:01
So at some point, it had been set into motion, but that force is not on the box currently or on the objects.
01:09
So the only thing it's experiencing that's bringing it to a stop is acceleration from friction.
01:16
So the net force in this case, in the horizontal, is mass times acceleration.
01:22
It is accelerating...
