JEE Main On 8 April 2017 Question 30
Question: In a physical balance working on the principle of moments, when 5 mg weight is placed on the left pan, the beam becomes horizontal. Both the empty pans of the balance are of equal mass. Which of the following statements is correct?
Options:
A) Every object that is weighted using this balance appears lighter than its actual weight
B) Left arm is shorter than the right arm
C) Both the arms are of same length
D) Left arm is longer than the right arm
Show Answer
Answer:
Correct Answer: B
Solution:
- $F_1d_1=F_2d_2$ Consider mass of pan be m,as the mass of the pan is same initially, so when the weight is not placed on the pan the force acting will be same as mg on both sides, ∴ After the weight is placed on left pan, $(5mg+mg)d_1=mgd_2$ $d_2=6d_1$ Hence the left arm(in which 5mg was placed) is shorter than right arm.
