Q â€‹A rope lies on a table such that a part of it hangs down the table When - Physics -

Question

Q â€‹A rope lies on a table such that a part of
it hangs down the table When the length of hanging is 1/3 Of entire
length the rope just begins to slide The coefficient of friction
between the rope an
the table is :
(1) 2/3
(2) 1/2
(3) 1/3
(4) 1/6

Sd · Answer

Gravitational force doesn't act directly on any element of non-hanging part of rope, and tension from both sides on any element of the non-hanging part of rope get cancelled out, the only force driving the rope forward is the friction force which acts only on the non-hanging part, and thus friction acts in forward direction that is direction of motion of rope. Thus, in this case work done by friction is positive ( so we do not add the negative sign in front of work done by friction ).

Q. ​A rope lies on a table such that a part of it hangs down the table. When the length of hanging is 1/3 Of entire length the rope just begins to slide The coefficient of friction between the rope an the table is : (1) 2/3 (2) 1/2 (3) 1/3 (4) 1/6

Q. A rope lies on a table such that a part of it hangs down the table. When the length of hanging is 1/3 Of entire length the rope just begins to slide The coefficient of friction between the rope an
the table is :
(1) 2/3
(2) 1/2
(3) 1/3
(4) 1/6