## Work and Energy

 Quote by benrocks1 Oh so the kinetic energy is 0 because it is not in motion?
Exactly!

I am just realizing that we have a sign error here, perhaps this was the source of your confusion.

It should be 1/2mv^2 + mgh = constant right? Sorry I did not notice this before.
 thanks so much for your all your help and time!

 Quote by benrocks1 While the kinetic energy increases, the potential energy will decrease. Is that correct?
ONLY for certain problems.

Consider a pendulum swinging back and forth with no air resistance or friction.

At the top of the swing:

PE = Maximum = mghmax where h is measured from the bottom of the swing
KE = Zero because it stops momentarily

At the bottom of the swing:

PE = Zero
KE = Maximium (= 0.5mV^2)

At any point in between:

PE + KE = Constant = mghmax
 Went back and corrected sign error in my posts (don't want to confuse anyone coming along later). Can't believe I can post so many times and not notice this, what I get for being half asleep I guess

 Tags kinetic energy, potential energy