0

Guest

Courses New

A system of frictionless pulleys P 1 and P 2 are shown in figure. Neglecting the weights of the pulleys, the minimum pull needed at A to lift a load W will be (1) W/2 (2) W/3 (3) W (4) Below W/3 Pls explain stepwise and in detail.

A system of frictionless pulleys P1 and P2 are shown in figure. Neglecting the weights of the pulleys, the minimum pull needed at A to lift a load W will be
(1) W/2
(2) W/3
(3) W
(4) Below W/3
Pls explain stepwise and in detail. 

Question Image
Grade:12th Pass

1 Answers

Utsav Basu
70 Points
6 years ago
The min force required to pull the weight up is actually the min force required to prevent the weight from falling. Thus, to simply solve this question we can solve it backwards. 
 
So, if we assume that the weight is not falling, a force equal to its weight must act upon it, which is W. This force is provided by the tention of the string wrapped around pulley P1, and is divided equally upon its two strands. Thus, the tension on the right strand = W/2
 
Now, notice that this force is actually provided by the pull at A. 
Thus, the min pull required to pull the weight up = W/2
Option (1) is correct.

Think You Can Provide A Better Answer ?

Other Related Questions on Mechanics

View all Questions »

ASK QUESTION

Get your questions answered by the expert for free

Answer and earn gift vouchers

Win Gift vouchers upto Rs 500/-

View courses by askIITians

Design classes One-on-One in your own way with Top IITians/Medical Professionals

Click Here Know More

Complete Self Study Package designed by Industry Leading Experts

Click Here Know More

Live 1-1 coding classes to unleash the Creator in your Child

Click Here Know More

a Complete All-in-One Study package Fully Loaded inside a Tablet!

Click Here Know More