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Chapter 19:2 Orbital Motion (inertia, gravity, and weightlessness)
Learning target: __________________________________________________
________________________________________________________________
FORCE
Newton realized that the force that holds the moon in
orbit acts over long distances between objects that are
not in contact.
A FORCE is a ___________ or a ___________.
Forces act on bodies in 2 ways…
Contact Forces
___________ contact is needed to create push or
pull.
Examples: Applied Force, Tensional Forces
Distance Forces
NO ___________ contact is needed to create force.
Examples: ______________ Forces, E-M Forces
A Universal FORCE
Gravity = The force of ___________ between all objects in the universe.
Newton's Law of Universal Gravity – Every object in the Universe ____________
every other object.
Strength of GRAVITY
Gravitational Strength is
determined by:
MASS
DISTANCE
The force of gravity increases as the mass of the objects _____________.
The force of gravity decreases as the mass of the objects ___________.
(Direct Proportion – as one variable goes up or down the other variable also goes up
or down)
The force of gravity increases as the distance between two objects __________.
The force of gravity decreases as the distance between two objects __________.
(Indirect Proportion – as one variable goes up or down, the other variable goes the
opposite way)
MASS

WEIGHT
Mass is the amount of ___________ in an object.
Weight is due to your _________ and the acceleration due to ___________.
(“g” = 9.8m/sec.²)
Weightlessness
Zero g - A sensation experienced by an individual when there are no _________ forces
acting on that individual. (An example is when in a state of free-fall.)
_________ and ___________ CREATE a sensation of Weightlessness.
Inertia -The tendency of objects to resist a change in ________.
Forces don’t keep objects moving ___________ does.
Newton’s 1st law of Motion
Objects in motion will remain in _________,
objects at rest will remain at ________
unless acted upon by an ________ ________.
ORBITAL MOTION
Newton concluded that two factors combine to keep Earth in orbit around the sun and
the moon in orbit around the Earth.
Orbital motion is a result of the combination of an object’s forward __________ and
the downward pull of __________.
ORBITING SATELLITES
Since Earth is CURVED, objects with enough
__________ will stay in a state of freefall, orbiting
Earth, creating the sensation of
__________________.
Gravity & Motion Review Questions
Read the words in the box. In each sentence below, fill in the correct word.
Force
Pull
Gravity
mass
1. The force that attracts all objects toward each other is called
_________________.
2. The amount of matter in an object is called ______________________.
3. A push or pull is called a __________________.
---------------------------------------------------------------------------------------------------4. Circle the letter of each sentence that is true about gravity.
a. Gravity attracts objects toward each other.
b. The more mass an object has, the greater its force of gravity is.
c. The force of gravity is stronger when two objects are farther apart.
5. Is the following sentence true or false? Gravity is a force that pushes all objects
away from each other.
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Read the words in the box. In each sentence below, fill in the correct word.
Inertia
Motion
Gravity
6. A moving object keeps moving because of __________________.
7. The moon keeps moving ahead because of __________________.
8. Earth’s _________ keeps the moon from moving in a straight line.
Draw arrows on the diagram to
show:
9.
the direction of the sun’s
pull of gravity on Earth
10. the direction of Earth’s pull
of gravity on the moon