Find Energy of 2kg Stone After Projection from 15m Cliff

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To find the energy of a 2 kg stone projected horizontally from a 15 m cliff at 20 m/s just before it touches the ground, both potential and kinetic energy must be considered. The potential energy lost as it falls is converted into kinetic energy, maintaining the principle of conservation of energy. The total energy just before impact includes the initial kinetic energy and the potential energy at the height of the cliff. The calculations lead to a total energy of 700 J just before the stone hits the ground. Understanding the conservation of energy principle is key to solving this problem.
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Homework Statement



A stone of mass 2 kg is projected horizontally with a speed of 20 m/s from a cliff which is 15 m above the ground. Find the energy possessed by the stone just before touching the ground.

A. 400J
B. 500J
C. 600J
D. 700J

Homework Equations





The Attempt at a Solution


I can't get the answer. How can I achieve it?
I think 'just before touching the ground' means when the stone is still moving, but I don't know the velocity at this instant. And at the same time, the stone is losing potential energy, how can I manage this?
 
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HINT: Inital Energy = Final Energy

Consider 'just before the stone touches the ground' to be the stone has actually hit the ground but not lost any kinetic energy, the instant the stone touches the ground.
 
Ah... I've got it!
Thanks a lot!
 
lingling said:
Ah... I've got it!
Thanks a lot!
My pleasure :smile:
 

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