Gravity Notes Part 1

What is a Gravity? First described by Isaac Newton Observed an apple fall from a tree straight to the ground Concluded an invisible force was pulling the apple toward Earth

What is a Gravity? Gravity = a force that pulls objects toward one another All objects exert a gravitational pull on one another The one we experience the most is Earth’s gravitational pull

When you hold a book in the air it does not fall Gravity pulls down What is a Free Fall? When you hold a book in the air it does not fall Gravity pulls down Your hand pushes up Net force = 0N = no movement Hand = 50N Gravity = 50N

Net force = 50N down = movement down What is a Free Fall? When you let go it falls Gravity pulls down No other force acts Net force = 50N down = movement down Gravity = 50N

What is a Free Fall? Free fall = when gravity is the only force acting on an object This causes objects to accelerate downward Acceleration due to gravity = 9.8m/s2

What is a Free Fall? Example: It takes 5 seconds for a book to fall to the floor. If acceleration due to gravity is 9.8m/s2, what speed did the book reach before hitting the ground? S=A(T) = 9.8m/s2 (5s) = 49m/s S A T

What is a Free Fall? All objects, regardless of size or mass, fall at the same acceleration rate.

What is a Free Fall? All objects, regardless of size or mass, fall at the same acceleration rate.

Feather and Hammer Drop Which would hit the ground first? Why? Hammer vs. Feather Feather and Ball bearing

Table Small Ball Average Large Ball Average A B C D E F

In real life, some objects fall faster than others. Air resistance In real life, some objects fall faster than others. Ex: A basketball falls faster than a leaf. 5 seconds Gravity = 10N 2 seconds

This is due to air resistance Fluid friction against the object Some objects are more aerodynamic than others. Air Resistance Gravity

If air resistance becomes great enough, it equals the force of gravity This results in balanced forces Acceleration stops The objects stays at a constant speed = terminal velocity Air resistance =100N Gravity pull=100N

Any Questions?