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…

Inertia

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