wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

A man has fallen into a ditch of width d and two of his friends are slowly pulling him out using a light rope and two fixed pulleys as shown in figure. Show that the force (assumed equal for both the friends) exerted by each friend on the road increases as the man moves up . Find the force when the man is at a depth h.

Open in App
Solution

(a) At any depth 1, let the ropes make an angle θ with the vertical.

From the free body diagram

F cos θ+F cos θmg=0

2F cos θ=mg

F=mg2 cos θ

As the man moves up, θ increaes , i.e. cos θ decreases. Thus F increases.

(b) When the man is at depth "h"

cos θ=h(d/2)2+h2

F=mg2 cos θ

=mg2.[hl(d2)2+h2]

= mg4hd2+4h2


flag
Suggest Corrections
thumbs-up
49
similar_icon
Similar questions
View More
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Problem Solving Using Pseudo-Forces
PHYSICS
Watch in App
Join BYJU'S Learning Program
CrossIcon