00:01
So in this question we are given that there is a block of mass m which is given to us as 46 kgs.
00:09
It's being pulled by a force which is a constant force of 225 newtons.
00:16
And we are told that there are two lengths over which on a horizontal surface it moves.
00:22
So it moves on first 11 meters which has no friction.
00:28
And then the second 10 meters of its motion is on a surface with the friction coefficient of point 2.
00:35
So we are asked when it reaches the end of this 10 meters, what is the velocity? let's call it v2.
00:41
Let's call the velocity the block at the end of this stage as v1.
00:46
So the first part of the problem means we have to take into account work done, let's call this region 1 and distance 2.
01:02
So the work done during distance 1 is simply by the force.
01:06
There is no friction force so there is only a force that is acting let's call this f so f times d1 will be the work done on the block and this should be equal to the change in kinetic energy of the block given that the block starts from zero velocity so originally the block has no energy and then the force f does work during this distance d1 and gives some energy to the block which ends up being the kinetic energy the block at the end of the distance one so from here we we can say that the velocity or the kinetic energy in this case would be, let's call this kinetic energy at distance 1.
01:49
So kinetic energy at distance 1 is force which is 225 times the distance which is 11 and this gives us 2475 joules.
01:59
So this is the kinetic energy or the work done on the block at the end of distance 1.
02:06
So work done during distance 2 will now be part, two parts.
02:11
So the first will be f, the same force over distance 2...