Tuesday 23 April 2013

4.13 understand how conservation of energy produces a link between gravitational potential energy, kinetic energy and work

The best way to explain this idea is with a swinging pendulum:
At the top of the swing, it will have its highest gravitational potential energy (as its further from the earth); but it will have its lowest kinetic energy (it slows to a stop at the top point).
At the bottom of the swing, it will have its lowest gravitational energy (as it is closer to the earth); but it will have its highest kinetic energy (it goes very quickly past the bottom point).

Between the points work (force x distance) is constantly being done: the pendulum is moving through space.
Remembering that work done is equal to energy transferred, we can see that as work is done that moves the pendulum upwards, kinetic energy is transferred in to gravitational potential energy. When work is done to bring the pendulum downwards, energy is transferred from GPE to KE.

The pendulum demonstrates that energy is conserved, as then energy is constantly changing between different forms. The only reason that energy is lost from the pendulum, and it slows down, is that some energy is transferred into heat or sound.

maximum kinteic energy at lowest point of swing - minimum gravitational potential energy. at the highest point of swing there is no kinetic energy, and maximum gravitational potential energy.
bbc

9 comments:

  1. You are so awesome! Saved me from IGCSEs haha thank you so much :)

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  4. What other contexts can this be applied to?

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  5. You are such a life saver thanks so much!! :)

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  6. You are such a life saver thanks so much!! :)

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  7. This can be applied to anything going up and then back down again e.g if I have a kart and I push it up a hill (ignore the fact it takes my chemical energy initially) the kart moves up due to ke and at the top of the hill it is now at the peak gpe and it stops as it has reached its destination I.e the peak and when it goes back down again all the gpe is converted back into ke and so on ( but long winded )

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