GRAVITY AND MOTION
WHAT IS GRAVITY??
•
Gravity- the force that pulls objects towards one another
• This causes all objects in the universe with a mass to be “attracted” to each other
• This means that everything accelerates towards one another
GRAVITATIONAL FORCE
•
The strength of the force of gravity depends on two factors:
• The mass of the objects
and
• The distance between the objects
• The bigger the mass, the stronger the
attraction
• The larger the distance, the weaker the
attraction
THE LAW OF UNIVERSAL GRAVITATION
•
This law states that the force of Gravity acts between ALL objects in the universe…
THIS IS WHY
• We stay on Earth because we live on the surface(extremely close) and the Earth
is massive(large mass)
• The Earth and all other planets revolves around the sun because the sun is so
massive
WHY DON’T WE FEEL IT?
•
In order for a gravitational attraction to be felt, the mass of one of the objects must be
extremely large…
SIR ISAAC NEWTON AND ALBERT EINSTEIN
• Sir Isaac Newton discovered the concept of gravity, but
couldn't really explain where it came from.
• You might know of his other best known discoveries…
Newton’s Laws of Motion?
• Albert Einstein was the first to be able to explain
why gravity acts the way that it does
FREE FALL
•
When gravity is acting on an object, it is in “free fall”
•
On Earth, all objects near the surface accelerate 9.8m/s/s toward the center of the earth
•
So, all objects, no matter the shape or size, fall at the same speed…
•
Then why doesn’t a piece of paper and a book hit the ground at the same time??
•
Thoughts?? Why did a flat piece not work, but the same piece crumpled up did?
EARTH’S ORBIT AND GRAVITY
•
Gravity- a force that pulls objects towards one another
•
Inertia- an object in motion will always stay in motion unless acted upon by another force
THE RESULT…
•
Gravity pulls it in…..
•
Inertia keeps it moving…
•
Creating orbit…
MASS VS WEIGHT
•
Mass- the measurement of the amount of matter that makes up an object
• Will always be the same no matter gravitational pull
•
Weight- the measurement of the amount of pull of gravity on an object
• Will change depending on gravitational pull
•
So… guess your weight on another planet… say mars…and let’s find out