GRAVITYPhysical ScienceMr. Barry

Gravity is a Force

Every object in the Universe exerts a force on every other object

Gravity: force of attraction between two objects

Often this force is too slight to notice Can you feel the person next to you

pulling on you?

Discovery of Gravity

First discovered by Sir Isaac Newton

Included in his 3 Laws of Motion (to be covered later)

Did he really discover it or was it already there?

Calculating Gravity Gravity depends on:

1. The mass of the objects attracted to each other

2. The distance between the two objects

Because everything here on Earth is much smaller than the Earth and is relatively close to the Earth, gravity is considered a constant

g = 9.81 m/s2

Calculating Force of Gravity Your “force of gravity” is more commonly known as your weight

W = mg W = weight (Newtons) m = mass (kg) g = gravity constant (9.81 m/s2 , always

the same on Earth) Add this to your equation sheet!! This is why weight and mass are not

the same thing!!

Gravity = Constant

Everything, no matter how massive, has the same gravitational acceleration

If the only force on two objects is gravity, they will fall at the same rate

Famously discovered by Galileo at the Leaning Tower of Pisa

Vertical Motion

Objects accelerate downward because of gravitational force

“Free Fall” This means

their speed increases the longer they fall