Question

When you are holding still a bag of apples having a weight of 10 kg at a height of 2 meters, how much is the work you are doing?

  

zero joules

   

2 joules

   

20 joules

   

200 joules

   

none of the above

B)

Two friends go hiking to a mountain. Friend A has a mass of 60 kg while friend B has a mass of 50 kg. When they reach the top of the mountain, which of the two did more work?

  

They both did the same amount of work.

   

We cannot decide. We must know the height of the mountain.

   

Friend A

   

Friend B

Answer 1

Part (A) :

Work done is defined as the multiple of displacement and force in direction of displacement. OR Change in energy.

In this case when we are holding the bag still, it's potential and kinetic energy is constant and displacement is zero. Hence :

Work done = Zero Jules.

Part(B) : In this case,

Work Done = change in potential energy.

Potential energy is given by formula : U = mgH

m = mass of body

g = gravitational constant

H = hight.

Initial potential energy of both A and B is zero.

So Friend with higher mass will gain higher potential energy Hence he will do more work.

Friend A with 60 Kg mass will do more work.

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