00:01
Hello, in the question we have given that a person is pulling a block across a surface with a friction f at a constant speed by applying a force f directed at an angle of 25 degree above the horizontal.
00:15
So, we will first draw the free body diagram over here.
00:22
So, fbd represents, so it is, i am abbreviating free body diagram as fbd over here.
00:29
So, we have this block.
00:30
So, i am drawing it as a block.
00:34
So, now this force, so this is the x -axis which we are having.
00:44
So, now this force is at an angle of 25 degrees.
00:51
So, this f prime is at an angle of 25 degrees from the horizontal.
00:56
So, this is my horizontal.
00:58
So, now we will resolve this force first.
01:07
So, what they are saying is take weight of the block to be w and the normal force to be n.
01:13
So, which of the following relations must be true? so, the weight of the block, so it will be like this.
01:19
So, this is w.
01:22
Then there will be a frictional force over here in this direction.
01:28
So, this is f, this cursive f and then we will have a normal force.
01:34
I am drawing it this way.
01:35
So, here we will have the normal and now if we resolve the component of this force, so f prime, so this component will be f prime cos of 25 degrees and this component out here will be, so this component over here, sorry, so this component, the vertical component of this force will be equal to f prime sin of 25.
02:10
So, now let us draw.
02:12
So, we have the vertical and the horizontal components.
02:16
So, let us see the first vertical component...