SATHEE: Rotational Motion Question 131

Rotational Motion Question 131

Question: A horizontal heavy uniform bar of weight $W$ is supported at its ends by two men. At the instant, one of the men lets go off his end of the rod, the other feels the force on his hand changed to

Options:

A) $W$

B) $\frac{W}{2}$

C) $\frac{3 W}{4}$

D) $\frac{W}{4}$

Show Answer

Answer:

Correct Answer: D

Solution:

[d] Let the mass of the rod is $M \Rightarrow$ Weight $(W) = M g$

Initially for the equilibrium

$F + F = M g \Rightarrow F = M g / 2$

When one man withdraws, the torque on the rod $τ = I α = M g \frac{l}{2}$ $\Rightarrow \frac{M l^{2}}{3} α = m g \frac{l}{2}$

As $I = M l^{2} / 3$

$\Rightarrow$ Angular acceleration, $α = \frac{3}{2} \frac{g}{l}$

And linear acceleration

$a = \frac{1}{2} α = \frac{3 g}{4}$

Now if the new normal force at A is F’ then

$M g - F^{'} = M a$

$\Rightarrow F^{'} = M g - M a = M g - \frac{3 M g}{4} = \frac{M g}{4} = \frac{W}{4} .$

Rotational Motion Question 131

Question: A horizontal heavy uniform bar of weight $W$ is supported at its ends by two men. At the instant, one of the men lets go off his end of the rod, the other feels the force on his hand changed to

Options:

Answer:

Solution:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

Rotational Motion Question 131

Question: A horizontal heavy uniform bar of weight W is supported at its ends by two men. At the instant, one of the men lets go off his end of the rod, the other feels the force on his hand changed to

Options:

Answer:

Solution:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

Menu

Question: A horizontal heavy uniform bar of weight $W$ is supported at its ends by two men. At the instant, one of the men lets go off his end of the rod, the other feels the force on his hand changed to