1. Do now

2. Potential energy = mgh = Fgh = (10N)(5m) = 50 Nm = 50 J
Do now
Potential energy = mgh = Fgh = (10N)(5m) = 50 Nm = 50 J
ET = PE + KE + Q
55J = 50 J + 0J + 5J

4. We now consider problems in which Q ≠ 0
Energy “Loss”
Energy can never by truly destroyed, but it can be converted into non-mechanical forms (mainly heat) that are not ‘useful’.
We now consider problems in which Q ≠ 0
Q = Work necessary to overcome friction (it can also represent an increase in energy/temperature)

6. Constant velocity and Constant mass = Constant kinetic energy (1/2 mv^2)
Horizontal Track = Constant Potential energy
Sliding along a rough track = friction = increase in internal energy, only (2)

7. 7 minutes to complete worksheet

8. Review

9. Extra Credit Last week’s quiz will not count as extra credit
There will be a 5-point extra credit question on the exam available to everyone that is very similar (no partial credit)