Question

Explain how potential energy, kinetic energy, and total mechanical energy change form when an archer releases an arrow from a bow. What happens to some of the mechanical energy as the arrow meets the resistance of air (friction)?

Answer 1

Okay....so lets think about potential energy first.... P.E = mgh

the arrow begins at rest....At this point there is MAXIMUM potential energy
The arrow is then released, and potential energy then transfers to kinetic energy as it is now moving

Now move onto kinetic energy K.E = 1/2 mv^2

At the beginning...when the arrow is at rest...the Kinetic Energy is at its minimum (or zero)
and as it is released and potential energy is transferred to kinetic energy, it rises

Answer 2

okay, i am following so far :)

Answer 3

The total mechanical energy is just the sum of these 2 things

E = P.E + K.E

Beginning we have

E = P.E

After the bow is released...we still have SOME potential energy, but it is transferring all into Kinetic energy...also they mention air resistance...this will just be a force that will slow down the arrow thus making the kinetic energy lesser...because remember

K.E = 1/2mv^2 if 'v' is smaller because of air resistance, then the total K.E is smaller

And finally at the very end the total mechanical energy is complete kinetic energy

E = K.E

Answer 4

ohh okay! so with the archer, it's at rest (potential energy) that transfers into kinetic energy once it's in motion but then it becomes mechanical energy as it slows down, finally coming to a rest again at kinetic energy?

did i understand that correctly? haha :P

Answer 5

Hmm...I'm not sure lol

It begins at Maximum potential energy (K.E = 0)
Potential transfers into Kinetic
Ends at Maximum Kinetic (P.E = 0)

It doesn't "become mechanical energy" at any point because "mechanical energy" is purely the sum of the potential and kinetic energies at any given point

Answer 6

And remember, this is just what happens when the archer releases the bow, we dont even need to account for what happens when the bow hits the ground and goes to rest again

Answer 7

ohh okay! :) so just Max PE--> KE --> max KE ?

and so how would we explain the part when it hits the ground and rests again? :O

Answer 8

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Answer 9

* ?