Gravity is the force that keeps Earth and other large celestial bodies in orbit around the Sun. Sir Isaac Newton first hypothesized that the same force of gravity that causes apples to fall to the ground also causes the Moon to orbit Earth. Gravity is caused by the bending of spacetime due to mass. More massive objects cause greater bending. This bending is what we perceive as the force of gravity. Gravity depends on the masses of the interacting objects and the distance between them - the greater the masses and the closer the distance, the stronger the gravitational force. All objects fall at the same rate in a vacuum where air resistance is not a factor.

2. WHAT KEEPS EARTH IN ORBIT AROUND
THE SUN?

3.  What stops a body from streaming off into outer space?
 GRAVITY
 To understand gravity let’s take a look at the past…
GRAVITY
 Sir Isaac Newton was
the first person to
hypothesize that the
force that pulls an
apple to the ground was
the same force that
pulls the moon toward
Earth, and it is this
force that keeps big
objects like the Moon
and Earth in orbit (along
with inertia).

4. Elegant Universe – Gravity’s Story!
But if gravity makes things fall or attracted to other objects…how
exactly does gravity work?

5. The Universal Law of Gravity is the force of
attraction between all objects in the universe.
GRAVITY
Why?
 Because all objects have MASS.
How?
 By bending the space time fabric
 The more massive the object, the
more it bends.
 It is this bend in space time that we
feel as gravity.
Measured in Newton’s
“g” on Earth accelerates at
9.8m/s2

6. DRAW A PICTURE OF HOW GRAVITY
WORKS?

7. LAB – GRAVITY AND RATE OF FALL

8. LAB – GRAVITY AND RATE OF FALL
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All objects fall to the ground at the same rate, the flat paper took a longer time
to reach the ground because of air resistance.
Only the uncrumpled (flat) paper
Air resistance slowed down the flat uncrumpled paper

9. Yes – Take away air resistance and each item would hit the ground at the same
time.
Air resistance was no longer a factor slowing down the paper.
They would hit the ground at the same time because all objects fall on Earth at
9.8 m/s/s.
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10. GRAPHING THE LAW OF GRAVITY

11. GRAPH 1 - GRAVITY VS. MASS

12. GRAPHING THE LAW OF GRAVITY

13. GRAPH 2 - GRAVITY VS. DISTANCE

16. STRENGTH OF GRAVITY
What determines the strength of gravity?
MASS –
 The product of masses
between two objects.
DISTANCE –
The distance
squared between
two objects.

17. BRAINPOP - GRAVITY

18. STRENGTH OF GRAVITY
The force of gravity increases as
the mass of the objects increase.
(Direct Proportion)
0
200
400
600
800
1000
1200
1400
1600
1800
2000
0 10 20 30 40
GravitationalForce(Newtons)
Distance Squared Between Planets (km squared)
Gravitational Force vs. Distance
Squared
0
500
1000
1500
2000
2500
0 200 400 600 800
GravitationalForce(Newtons)
Product of Planet Masses (kg)
Gravitational Force vs. Product
of Masses
Gravity decreases as the
distance between two objects
increase. (Indirect Proportion).

19.  Mass- is the amount of matter in an
object
 Weight- is the force of gravity on
an object
 The greater the mass the greater
the force (weight)
MASS VS. WEIGHT

20. FREE FALLING – NOW I’m Free
Falling
All objects,
no matter
their mass,
fall to Earth
at a rate of
9.8 m/s²
HOWEVER,
Air resistance
can cause
some objects
to reach their
terminal
velocity.
FREE FALL ON
THE MOON

21. THE FEATHER ON THE MOON!

22. STUDENT DROPS

23. STUDENT DROPS