Transcript Warm Up- Work silently to receive full credit

Warm Up
1. What are units for velocity?
2. What are units for
acceleration?
3. What is the equation for
acceleration?
4. What is the equation for
velocity?
Objective
• I CAN:
– Relate gravitational force to mass and
distance
Gravitational Force
The force of attraction between all masses
in the universe
Very Important!!
• Responsible for:
– Creation of black holes
– Structure of galaxies
– Expansion of the universe
– Things falling to the ground
– Humans only being able to jump so high
Universal Gravitation
Gravity affects everything!
Universal Gravitation
Gravity affects everything!
Universal Gravitation
Gravity affects everything!
Universal Gravitation
Gravity affects everything!
Universal Gravitation
Newton’s Law of Universal
Gravitation:
(
Fg = G m1m2
2
r
)
Universal Gravitation
Fg = G m1m2
2
r
Fg = Gravitational Force
-11
G = Constant = 6.7 x 10
m1 = mass 1 m2 = mass 2
r = dist b/w center of the 2
• Gravitational constant is CONSTANT
(does not change)
• Mass- kg
• Distance- m
• Force- newtons (N) because that’s what
happens when you discover things
Newton’s Universal Law of
Gravitation
• Gravitational force- weakest of all forces
• How does it hold the planets in orbit????
• The planets are VERY large and VERY far
apart
What could explain an increase in
gravitational force?
• Fg = G m1m2
r2
What could explain a decrease in
gravitational force?
• Fg = G m1m2
r2
Effect of gravitational force
↑ mass causes ↑ Fg
↓ mass causes ↓ Fg
↑ distance causes ↓ Fg
↓ distance causes ↑ Fg
…but by how much???
• If the mass is multiplied by some number,
then Fg is multiplied by that number
• If the mass is divided by some number,
then Fg is divided by that number
What happens to gravitational force
if the mass of one object is
multiplied by 2?
• Fg = G m1m2
r2
What happens to the gravitational
force if the mass of both bodies is
multiplied by 2?
• Fg = G m1m2
r2
What happens to gravitational force
if the mass of both objects is
multiplied by 3?
• Fg = G m1m2
r2
What happens to the gravitational
force if the mass of one body is
multiplied by 3 and the mass of the
other body is multiplied by 1/2?
• Fg = G m1m2
r2
• If the distance is multiplied by some
number, Fg is divided by the SQUARE of
that number
• If the distance is divided by some number,
Fg is multiplied by the SQUARE of that
number
What happens to the gravitational
force if the distance between the
objects is multiplied by 2?
• Fg = G m1m2
r2
What happens to the gravitational
force if the distance between two
objects is divided by 2?
• Fg = G m1m2
r2
What happens to the gravitational
force if the distance between two
bodies is multiplied by 3?
• Fg = G m1m2
r2
Complete your worksheet
independently
How to calculate?
•
•
•
•
•
Multiply out m1xm2/r2
Multiply that times 6.7
Remember scientific notation?
Want one number in front of decimal
If move decimal left, exponent becomes
less negative
• If move decimal right, exponent becomes
more negative
Universal Gravitation
If two .08kg cheerios are
.03m apart, what is the
gravitational force between
them?
Universal Gravitation
If two .08kg cheerios are .03m
apart, what is the gravitational
force between them?
m1 = .08 m2 = .08
Universal Gravitation
If two .08kg cheerios are .03m
apart, what is the gravitational
force between them?
m1 = .08 m2 = .08 r = .03
Universal Gravitation
Fg = G m1m2
2
r
If two .08kg cheerios are .03m
apart, what is the gravitational
force between them?
m1 = .08 m2 = .08 r = .03
Universal Gravitation
Fg = G m1m2
2
r
If two .08kg cheerios are .03m
apart, what is the gravitational
force between them?
m1 = .08 m2 = .08 r = .03
Fg = (6.7 x
-11
10 )(.08
x .08)
2
(.03)
Universal Gravitation
Fg = G m1m2
2
r
If two .08kg cheerios are .03m
apart, what is the gravitational
force between them?
m1 = .08 m2 = .08 r = .03
Fg = (6.7 x
-11
10 )(.0064)
2
(.03)
Universal Gravitation
Fg = G m1m2
2
r
If two .08kg cheerios are .03m
apart, what is the gravitational
force between them?
m1 = .08 m2 = .08 r = .03
Fg = (6.7 x
-11
10 )(.0064)
(.0009)
Universal Gravitation
Fg = G m1m2
2
r
If two .08kg cheerios are .03m
apart, what is the gravitational
force between them?
m1 = .08 m2 = .08 r = .03
Fg =
-11
(6.7)x(10 )x(7.1)
Universal Gravitation
Fg = G m1m2
2
r
If two .08kg cheerios are .03m
apart, what is the gravitational
force between them?
m1 = .08 m2 = .08 r = .03
Fg =
-11
(6.7x7.1)x(10 )
Universal Gravitation
Fg = G m1m2
2
r
If two .08kg cheerios are .03m
apart, what is the gravitational
force between them?
m1 = .08 m2 = .08 r = .03
Fg =
-11
(48)x(10 )
N
Universal Gravitation
Fg = G m1m2
2
r
If two .08kg cheerios are .03m
apart, what is the gravitational
force between them?
m1 = .08 m2 = .08 r = .03
Fg = 4.8 x
-10
10 N
Complete your worksheet
independently
Cool Down
1. Does the gravitational constant ever
change?
2. How does gravitational force change is
distance is tripled?
3. How does gravitational force change if
the mass of both bodies is doubled?
4. HW: finish worksheet