Orbital Motion

Part 3

GRAVITY
& ORBITS

PART THREE:

ORBITAL
MOTION

1.What are the two factors that combine to
keep Earth and the moon on their orbital paths?
A)

B)

2.What term means ”the tendency of a moving object to
continue moving forward in a straight line”?

3.A washer is swung in a circle on a string as shown below.
Explain which arrow shows the path the washer will take,
if the string
were to break.

4.Explain what would likely happen to the moon’s orbit
around Earth if the moon became LESS massive.

Name _______________________________ Date _________________ Hour ____________

Unit 4: GRAVITY & ORBITS // Orbital Motion

• ORBIT = curved ______________ (or trajectory) taken by

large bodies in space

• Curved pathway formed from combination of

2 factors:
-- ___________________ pulling inward

--____________________ propelling forward

(this is the tendency of an object to resist
a change in its ___________________)

• The forces of inertia and gravity pull on the

object at a ______________ angle

• Model of orbital motion, with labels:

• For object to stay in orbit, inertia and gravity

must be _________________

--What happens if inertia (forward velocity) is greater
than gravitational force:
_______________________________
--What happens if gravitational force is
greater than inertia (forward velocity):
_______________________________

• A moon orbits a planet in a clockwise

direction. If the gravitational force of
the planet pulling on the moon were to
disappear, what path would the
moon take? Draw an arrow to
represent the moon’s new pathway.

But what keeps objects in orbit?

An ORBIT is the curved pathway (or trajectory)

taken by large bodies in space

Orbit is a result of two forces in balance:

gravity pulling

the object inward

inertia propelling
the object forward

inertia:tendency of an object to resist a change in its motion(somewhat like momentum)

QUESTION:
If gravity disappears, what will happen to a planet’s orbital path?

Open Ended

If gravity disappears, what will happen to a planet’s orbital path?

Let’s revisit Newton’s Law of Universal Gravitation

1.

If mass of an object increases, what happens to

the pull of gravity between them?

Gravity increases

Multiple Choice

If mass of an object increases, what happens to the gravitational pull?

• it increases

• it decreases

• it stays the same

2. What would happen to the moon’s orbit if it were

to become more massive?

*Gravity would
increase.

*This would upsetthe
balance that keeps it in
orbit.

*If gravitational pull is
stronger than moon’s
inertia, then the moon
would begin orbiting
closer to Earth.

Open Ended

What are the two factors that combine to keep Earth and the moon on their orbital path?

Multiple Choice

What term means ”the tendency of a moving object to continue moving forward in a straight line”?

• INERTIA

• GRAVITY

• MOTION