Question

In: Physics

Is work done when dragging a mass up a hill the same as the change in...

Is work done when dragging a mass up a hill the same as the change in potential energy?

Is work the same as energy? I am confused as to why

Expert Solution

Work is not the same as energy.

Work done a a body is equal to the net change in the kinetic energy of the body.

In your case if the body is dragged uphill by a constant velocity, only then will the work done be same as change in potential energy.

Take for example that friction is not acting on body

Initial velocity of block = v m/s

Initial height= 0 m

final velocity= v/ms

final height = h m

Work done is lifting body by height h metre= F d = (-mg)*h = -mgh (-mg because gravity acts downwards)

Change in Kinetic energy = (1/2) m (v1² - v2² ) = (1/2)m (v²-v²)=0

Change in Kinetic energy= change in Potential energy + Work done

=> Work done = - Change in potential energy

=> Work done= -mg (h2-h1)= -mgh

If the velocity of body doesnt remain constant , then

Work done= Change in kinetic energy- Change in potential energy- Work done by frictional forces.

Thus work and energy are not the same thing but change in energy of system gives work done on it.

genius_generous answered 8 months ago

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