1. Day 59 Physics UCM
LO: SWBAT perform calculate Fc and Ac LO: SWBAT Calculate Fg using NULG AGENDA Do Now – Complete UCM worksheet Notes Worksheet HW22 due Thursday

2. Newton’s Law of Universal Gravitation

3. Sir Isaac
Newton
( )

4. Rearth
60Rearth

5. Newton’s Law of Gravity
Constant of proportionality M1 M2 r

6. Cavendish, Henry (1731-1810) Measured G in 1798
G = 6.67 x Nm2/kg2

7. What is the force between Kiwi and a book?
F = (6.67 x 10-11)
(3)(4) 22
F = 2 x N
2 m
4 kg
3 Kg

8. What is the force between Kiwi and a book?
1,2
F = (6.67 x 10-11)
(3)(4) 22
F = 2 x N
or ??
F cat, book
F book, cat
4 kg
3 Kg

9. What is the force between the Earth and a book?
Wearth,book = Mbook (9.8 N/kg)
Wearth,book = (6.67 x 10-11Nm2)
(5.98 x 1024 kg) Mbook
(6.38 x 106 m)2
kg2
r = 6.38 x 106 m
Mearth = 5.98 x 1024 kg

10. But you ask why is “g” independent of mass?
F = m1g = Gm1mearth/r2
Note that the m1’s cancel on both sides and:
g = Gmearth/r2

11. Storey Musgrave (6 SST missions and Hubble Repair) m = 80 kg

12. What’s his mass?

13. What’s his weight?
648 N !

14. Apollo 17
Earth as seen from the Moon

15. What is the correct orbit of the space shuttle?

16. What is the correct orbit of the space shuttle?

17. At the surface of the Earth:
Wearth,Story = MStory (9.8 N/kg)
= (80 kg) (9.8 N/kg) = 784 N
rearth = 4000 miles

18. 400 miles above the surface :
Wearth,Story = MStory (8.1 N/kg)
= (80 kg) (8.1 N/kg) = 648 N
rearth = 4000 miles

19. Which force does the scale read?
NFS
WES
NPS
scale
WEP
NSP
person
Apparent Weight
True Weight

20. Apparent weight measured as the reading of the scale
equal to the normal force of the scale on your feet
equal to weight for a=0

21. Elevator
v = constant
a = 0
NSP
Apparent Weight
True Weight
WEP

22. Elevator
NSP
a is upward a
Apparent Weight
True Weight
WEP

23. Elevator
a is downward a
Apparent Weight
True Weight
NSP
WEP

24. Problem
You are riding down in an elevator carrying a 20 kg package in your arms. As the elevator gets to your floor, it slows with an acceleration of 2 m/s/s. What is the apparent weight of the package while the elevator is slowing?

25. Elevator g How large should the normal force be? a =9.8 m/s/s down NSP
WEP

26. Elevator Apparently Weightless?? g
How large should the normal force be?
a =9.8 m/s/s down
Apparently g
Weightless??
WEP

29. KC 135
INTERIOR