00:01
Hello, we have a block, the force f applied this way and friction mu r working that way.
00:13
Now the weight of the block is mg and reaction is r.
00:18
So from perpendicular equilibrium r is equal to the weight and so friction which is equal to mu r is simply mu mg.
00:29
So the net force is the pulling force minus the opposing friction.
00:37
So that will be 297 minus friction which is coefficient times mg because r equals mg.
00:58
So times 90 times 9 .8 which is negative 16 point, well negative 17 newton.
01:10
So if we assume motion is towards the right then this will be towards the left that is opposite the motion.
01:30
So this is a retarding force.
01:33
It will cause a retardation or a deceleration.
01:44
The work done by the retarding force is force times distance and that is minus 12 .74 joules negative because it is a work done by a retarding force.
02:12
Now to calculate the final velocity we use the work energy principle...