**Scenario I:**

m = 20 kg

Displacement of the object, s = 4 m

W = Fs cosθ

θ = It is the angle between the force and displacement

Fs = mgs cosθ

W = mgs cosθ = 20 x 4 x 9.8 \( cos 90^{\circ}\)= 0

\( ( cos 90^{\circ} = 0 )\)

**Scenario II:**

Mass = 20 kg

S = 4 m

The applied force direction is same as the direction of the displacement.

θ =\( 0^{\circ}\)

\( Cos 0^{\circ}= 1\)

W = Fs cosθ

= mgsθ

= 20 x 4 x 9.8 x \( cos 0^{\circ}\)

= 784 J

Thus, the work done is more in the second scenario.

Answered by Pragya Singh | 1 year agoA person trying to lose weight (dieter) lifts a 10 kg mass, one thousand times, to a height of 0.5 m each time. Assume that the potential energy lost each time she lowers the mass is dissipated.

**(a)** How much work does she do against the gravitational force?

**(b)** Fat supplies 3.8 × 10^{7}J of energy per kilogram which is converted to mechanical energy with a 20% efficiency rate. How much fat will the dieter use up?

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A trolley of mass 300 kg carrying a sandbag of 25 kg is moving uniformly with a speed of 27 km/h on a frictionless track. After a while, the sand starts leaking out of a hole on the floor of the trolley at the rate of0.05 kg s^{–1}. What is the speed of the trolley after the entire sandbag is empty?

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