Question

A woman moves the 10g object shown in a vertical plane from position x to position y along a circular track of radius 20m. The process takes 0.75 minutes. The work done by the woman is about?

Answer 1

Given:

Mass of object = 10g = 0.01 kg

Radius of circular track = 20m

Time taken to move the object from x to y= 0.75 minutes = 45 seconds

To find:

The work done by woman.

Solution:

The work done by woman will go in raising the potential energy of the object and the kinetic energy to move it from point x to y.

Potential energy of block at point y PE = m*g*h

h will we twice the diameter of the circle.

= 0.01*10*40 = 4J

Kinetic energy KE = mv^2/ 2

velocity v = displacement/ time

Therefore v = h/ time = 40/ 45 = 0.89 m/s

KE = 0.01*(0.89)^2 /2

= 0.01*1.126 / 2

= 0.0063 J

Total energy spent = 4J + 0.0063J = 4.0063J

Therefore work done by woman = 4.0063J.

Option C is the correct answer.