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Gravity
And
Inertia
ORBITAL MOTION
WHAT DO WE KNOW?
We know that Earth rotates on its axis as it revolves around
the sun in its orbit.
The combination of Earth’s tilt and this revolution causes us
to experience dif ferent seasons (angle of rays/length of days).
WHAT DO WE KNOW?
In order to understand how earth stays in its orbit, we need to
know what a force is?
A force is a push or pull
WHAT IS A FORCE?
Equal Push/Pull Greater Push than Pull Less Push than Pull
Forces and Motion – Phet
UNBALANCED
PHET – FORCES AND MOTION
In order to understand how earth stays in its orbit, we need to
know what a force is?
A force is a push or pull
WHAT IS A FORCE?
Equal Push/Pull Greater Push than Pull Less Push than Pull
Forces and Motion – Phet
UNBALANCEDBALANCED
Net = 0 Net = 0 Net = 0
In order to understand how earth stays in its orbit, we need to
know what a force is?
A force is a push or pull
WHAT IS A FORCE?
A force can act on a body in 2 ways
1. Contact Forces
Physical Contact is needed to create a push or pull
Example: Applied Forces (push) or tensional forces
(a pulley)
2. At a Distance Forces
NO physical contact is needed to create a push or
pull
Example: Electromagnetic Forces or Gravitational
Forces
Forces give an object the energy to
move,
stop moving, or
change direction.
WHAT IS A FORCE?
When you write with a pen you exert a force.
When you peddle you bike,
blow your nose,
turn on a faucet,
chew your gum,
or swim in a pool,
you are exerting forces on other objects.
We would never be able to move without exerting forces on things…
With any great force comes great opposition!
Ying is to Yang as Motion is to ________________.
FRICTION
A force that opposes motion by acting in a direction directly opposite
to the objects motion.
Without Friction, an object set in motion will continue in
motion and move at a constant speed FOREVER!
IN SPACE THERE IS…NOTHING…THEREFORE NO FRICTION.
WHAT IS A FORCE?
Once a force is applied to an object…Inertia takes over!
Newton’s 1st Law of Motion governs this motion…
Objects in motion will remain in motion. Objects at rest will remain at rest unless acted upon by an outside force.
Inertia is the tendency of an object to resist a change in motion.
In other words…
Forces DO NOT keep objects moving INERTIA does…
and this motion continues because there is no friction to stop this forward motion.
Newton’s 1st Law - Inertia
1. Describe Newton’s first law of motion.
2. Describe why a moving object on earth would stop.
3. Describe why Earth will not stop in space.
CHECK POINT – REVIEW QUESTIONS
