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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

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**Newton’s Law of Universal Gravitation**

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Sir Isaac Newton ( )

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Rearth 60Rearth

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**Newton’s Law of Gravity**

Constant of proportionality M1 M2 r

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**Cavendish, Henry (1731-1810) Measured G in 1798**

G = 6.67 x Nm2/kg2

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**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

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**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

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**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

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**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

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

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What’s his mass?

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What’s his weight? 648 N !

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Apollo 17 Earth as seen from the Moon

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**What is the correct orbit of the space shuttle?**

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**What is the correct orbit of the space shuttle?**

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**At the surface of the Earth:**

Wearth,Story = MStory (9.8 N/kg) = (80 kg) (9.8 N/kg) = 784 N rearth = 4000 miles

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**400 miles above the surface :**

Wearth,Story = MStory (8.1 N/kg) = (80 kg) (8.1 N/kg) = 648 N rearth = 4000 miles

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**Which force does the scale read?**

NFS WES NPS scale WEP NSP person Apparent Weight True Weight

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**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

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

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Elevator NSP a is upward a Apparent Weight True Weight WEP

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Elevator a is downward a Apparent Weight True Weight NSP WEP

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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?

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

WEP

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**Elevator Apparently Weightless?? g**

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

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KC 135 INTERIOR

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