newtons universal law of gravitation. factors affecting the gravitational force mass distance
TRANSCRIPT
Newton’s Universal Law of Gravitation
Factors Affecting the Gravitational Force
mass
distance
Mass
m1 m2
force varies directly with masses
Fg α m1 m2
decrease mass forcedecreased
Distancer
increase r
forcedecreased
Force varies inversely with distance squared
Fg α 1/r2
m1 m2
Fg α -------- r2
Fg
m1 m2/r2
slope = G
Fg α m1m2
Fg α 1/r2
G = 6.67 x 10-11 N m2/kg2
A 1000 kg car and a 2000 kg truckare 0.50 m apart.
Gravitational force: 5.3 x 10-4 N
Computing mass of Earth
radius of Earth: 6.37 x 106 m
1.00 kg mass has a weight of 9.81 N
mass of Earth: 5.97 x 1024 kg
2F
4F
¼ F
4F
F
“g”
gravitational field – weight per mass
wtg Fg
g = ------ = ------ mass m
G M= ------ r2
M = planet mass
Effect of changing variables GM g = ----- r2
if M doubles: if r doubles:if M & r doubles: if r becomes ½:
2g
¼ g
½ g
4g
Mars mass: 11% mass of Earthradius: 53% radius of Earth
gravitational field for Mars?
0.39 gE = 3.84 N/kg
M M
M
s
s s
Net gravitational force on bottom mass?
√3 GM2/s2
G m1 m2
Fg = ---------- r2
= weight
What would happen to your weight if:
Earth had twice mass but the same radius:
Earth had twice radiusbut same mass:
Twice weight
¼ weight
What is “g” at top of Mt. Everest(8848 m elevation)?
9.77 N/kg = 9.77 m/s2