Question

A meter scale of mass 400 gm is lying
horizontally on the floor. If it is to be held
vertically with one end touching the floor, the
work to be done is
1) 61 24J 3) 403 4 2 J
RAYANAGROUP​

Answer 1

Dear Student,

◆ Answer - (4)

W = 2 J

● Explanation -

When meter-scale is lying down, center of mass is touching ground.

PEi = m.g.h1

PEi = 0.4 × 10 × 0

PEi = 0 J

When meter-scale is held up center of mass is at height of 1/2 = 0.5 m.

PEf = m.g.h2

PEf = 0.4 × 10 × 0.5

PEf = 2 J

Work done in lifting the scale will be equal to change in potential energy of its center of mass.

W = PEf - PEi

W = 2 - 0

W = 2 J

Therefore, work to be done is 2 J.

Hope that's all...