warm up 1.what are units for velocity? 2.what are units for acceleration? 3.what is the equation for...

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

Gravity affects everything!

Universal Gravitation

Newton’s Law of Universal Gravitation:

Fg = G m1m2

r2


( )

Fg = G m1m2

r2

Fg = Gravitational Force

G = Constant = 6.7 x 10-11

m1 = mass 1 m2 = mass 2r = 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


r2

What happens to gravitational force if the mass of both objects is


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

If two .08kg cheerios are .03m apart, what is the gravitational force between them?



m1 = .08 m2 = .08



m1 = .08 m2 = .08 r = .03



m1 = .08 m2 = .08 r = .03

Universal GravitationFg = G m1m2

r2

If two .08kg cheerios are .03m apart, what is the gravitational force between them?m1 = .08 m2 = .08 r = .03

Fg = (6.7 x 10-11)(.08 x .08) (.03)2


r2


Fg = (6.7 x 10-11)(.0064) (.03)2


r2


Fg = (6.7 x 10-11)(.0064) (.0009)


r2


Fg = (6.7)x(10-11)x(7.1)


r2


Fg = (6.7x7.1)x(10-11)


r2


Fg = (48)x(10-11) N


r2


Fg = 4.8 x 10-10N


r2

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

warm up 1.what are units for velocity? 2.what are units for acceleration? 3.what is the equation for...

Documents

distance slide

number slide

gravitational force

universal gravitation

universe slide

negative slide

high slide

g m1m2 r