00:01
All right, so let's say we have somebody pushing on a crate that has a mass of 35 kilograms, and they're pushing with the force of 110 newtons, and we're told that the coefficient of static friction between the crate is 0 .37.
00:19
So part a asks, what's the maximum value of the frictional force? so this is going to be mu s times mg, so 35 times 9 .8 times 0 .37.
00:30
This is going to be 126 .91 newtons.
00:35
So part b asks, does the crate move? and the answer is no, because the force applied is less than 126 .9.
00:43
And so part c asks, what is the frictional force on the crate from the floor? and the frictional force is just going to be like negative 110 newtons so that it cancels out the force being applied.
00:59
And the box doesn't move.
01:01
For it's, you know, technically, yeah.
01:04
So anyway, d, we're told, a second worker pulls directly upwards on the crate.
01:10
What is the least vertical pull that allow the push to get the crate moving? so basically what we want is the force, the net force in the horizontal direction is going to be the force the worker applies, minus the frictional force, which is mu -s times the normal force...
