AP Physics

Gravity Near the Earth's Surface


NY - 9.803 m/s2

Denver - 9.796 m/s2

North Pole - 9.832 m/s2



mg = GmmE

g = GmE

G = Gravitational constant = 6.67 x 10-11 Nm2/kg2


Ex) Mars has a mass 1/10 that of Earth and a diameter 1/2 that of Earth.  The acceleration of a falling body near the surface of Mars is most nearly

g = GmE





Substitute changes into equation

Answer 4 m/s2



Giancoli p.  131) 32, 30

Earth - mass
5.974 x 10²⁴ kg

Earth - Mean Radius

6,371 km


Ex) Prove that the orbital velocity of satellite does not depend on the mass

mv2 = GmmE
r r2



v = (GmE/r)-1

From we equation we see that orbital V and Period T is only determined by orbital radius

The smaller the
radius the .....

the greater
the orbital velocity and

 smaller period T


Astronauts in Space Station
 are NOT weightless!!!






Einstein's Conception of Gravity

The Elegant Universe - PBS




Mythbusters Moon Landing Hoax 4 HQ


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