Sir i am unable to understand how you calculated the work done by friction(you said that according to concept video work done by friction only depends on the horizontal distance) .Also, i am unable to find the video related to this concept. Please help.
9 years ago
by
Mohak Sharma
Ans
1
->
Work is the force multiplied by the displacement of point of application of force in the direction of force... Here same calculation is done for elemental displacements and then total work can be calculated...
9 years ago
by
Physics Galaxy
Ans
2
->
Sir but friction is a non-conservative force.So work done by friction should be force multiplied by pi*r/4
8 years ago
by
Karan Singh
Ans
3
->
Yes, sir, I agree. If frictional force is nonconservative and as written in your book path dependent then why have we taken simply R? Not pi*R
6 years ago
by
Ayushi Jain
Ans
4
->
The catch here is that the magnitude and direction of frictional force is changing with motion of the block. You consider the block at an angle theta with horizontal. Hence the normal reaction will be mgcos(theta). At this instant the corresponding frictional force will be the above times 'mu'.Now in further motion if block is displaced by an angular position d(theta) then the elemental work done by friction will be mu*mg*Costheta*R d(theta). Now integrate this from 0 to pi/2. You will get the answer.
6 years ago
by
Mohak Sharma