0:00
Hi.
00:01
Here this given problem is based upon two different figures.
00:05
In the first part of the problem, which is based upon the first figure over a rough surface there is a block, block whose weight is w and the force is acting in downward direction, force f making an angle theta with the horizontal in downward direction.
00:30
And the block, the crate, is moving with uniform speed.
00:37
So as it is moving with the uniform speed, so forward force acting on it, f cost theta, that will be equal to force of friction, f k.
00:47
So vertical component of the same force that will be f sine theta weight of the crate that is 1500 newton the force applied is having a magnitude 260 newton this angle theta that is 20 .0 degree so in this first part of the problem as the speed is constant means having no acceleration so no net force should be acting on the crate.
01:31
So the forward force f cost theta, it should be equal to force of friction, f k which will be given by mu k into normal reaction.
01:44
Here normal reaction that will be equal to the sum of downward forces means w plus f sine theta.
01:56
So we get an expression for coefficient of kinetic friction and that is f cost theta divided by w plus f sine theta...