##### Non conservative forces and systems

 Physics Tutor: None Selected Time limit: 1 Day

In a given system, there is positive work done and the potential energy is found to have increased. Can you tell if the amount of kinetic energy has increased, decreased, or stayed the same? Explain

May 26th, 2015

Yes, you can. The total energy of a system *must* remain constant. So E = kinetic energy + Potential energy.

If Potential Energy changes, E has to remain the system. So:

E = K + P

E = K + Increase in P

E must stay the same, so there must be a decrease in kinetic energy

TO put it another way, in simpler terms:

If E = 10, K = 5 and P = 5, then:

10 = K + P

10 = 5 + 5
Potential energy increases by 1

10 = 5 + 6, but that isn't right, so kinetic energy must have changed:

10 = 4 + 6

May 26th, 2015

but doesn't positive work mean that the total mechanical energy initial is less than total mechanical energy final?

May 26th, 2015

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May 26th, 2015
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May 26th, 2015
Dec 8th, 2016
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