Question

Please answer question number 30

Answer 1

Solution:-

Option(B) is wrong which states :-

The work done by the gravitational force is positive.

Step - by - Step - Explanation

The coolie lifts the bag opposite to the gravitational pull and as the angle made is 180°, hence the work done by the gravitational force is negative as the Displacement is against the Force(Weight)of the body.

It can be expressed as:-

W = F.S.cos(θ)

Here Force is the weight of the body.

W = 100 × 10 × 5 ×cos180° (θ = 180°)

W = 1000× - 5 (cos180° = - 1)

W = - 5000J

So, the work done by the gravity is negative

(- 5000J) .

So, third option is wrong which states that work done by the gravitational force is positive.