1. ELEVATOR –WEIGHT and NEWTON’S SECOND LAW

3. FNET = ma FN - mg = 0 FN = mg FN – mg = - ma FN – mg = ma FN = mg -ma
No Acceleration
Go up+ Speeding up ( +a)
Go up+ Slowdown (-a)
FN – mg = - ma
FN = mg -ma
FN= m (g- a)
FNET = ma
FN - mg = 0
FN = mg
FN – mg = ma
FN = mg +ma
FN= m (g + a)

4. Go down+ Slowdown ( +a)
Go Down +Speed up (-a)
Free Fall ( a = -g)
FN – mg = ma
FN = mg +ma
FN= m (g+a)
FN – mg = -mg
FN = mg -mg
FN= m (g- g) = 0
FN – mg = - ma
FN = mg -ma
FN= m (g-a)

5. ATWOOD MACHINE AND NEWTON’S LAW

6. Atwood’s Machine Calculate the acceleration of the elevator and the tension in the cable.
Example (a) Atwood's machine in the form of an elevator-counterweight system. (b) and (c) Free-body diagrams for the two objects.

7. ELEVATOR AND WEIGHT AND NEWTON”S LAW
A 65 kg woman descends in an elevator that briefly accelerates at 0.20g downward when leaving a floor.
During this acceleration, what is her weight and what does the scale read?
What does the scale read when the elevator descends at a constant speed of 2.0 m/s?

8. A-Plus Physics https://www.youtube.com/watch?v=a0KVxh8iPP4

9. A mover is trying to lift a piano up to a second story apartment
A mover is trying to lift a piano up to a second story apartment. He is using a rope looped over two pulleys as shown. What force must he exert on the rope to slowly lift the piano’s 2000 N weight?

12. Find the acceleration and the tension in the rope.
μ = 0.20
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