Slide 1: Gravity Define gravity, terminal velocity and free fall
Explain the universal law of gravitation Aristotle : Aristotle Ancient Greece around 400 BC
He believed that the heavier the object, the faster it falls. Slide 3: Galileo theorized that all objects will land at the same time when they are dropped from the same height.
Gravity – the attractive force between all objects in the universe. Slide 4: Objects fall to the ground at the same rate because acceleration due to gravity is the same for all objects. Slide 5: What is gravity? Galileo helped us understand gravity as a force that exists between the Earth and objects. Newton showed that the same force exists between all objects. Even today, no one knows exactly
why objects attract each other. It all starts with an apple… : It all starts with an apple… Isaac Newton 1655 The Law of Universal Gravitation : The size of the gravitational force depends on two things:
Mass of the objects
Distance between the objects The Law of Universal Gravitation What is weight? : What is weight? Weight is a measure of the gravitational force exerted on an object.
Since gravity is a force and weight is a measure of gravity, weight is expressed in newtons (N). Gravity &Acceleration : Gravity &Acceleration The rate at which objects accelerate towards Earth is 9.8 m/s2.
It is the same for all objects, regardless of their mass. 9.8 19.6 29.4 39.2 49 58.8 68.6 Air Resistance : Air Resistance The amount of air resistance depends on the size and shape of an object.
Gravity pulls an object down, towards the Earth. Air resistance pushes an object up, or away from the Earth. Free Fall : Free Fall When there is no air resistance, an object is in free fall.
An object is in free fall only if gravity is pulling it down and no other forces are acting on it. Terminal Velocity : Terminal Velocity The force of gravity is equal to the force of air resistance
This is the highest velocity reached by a falling object thus it has 0 acceleration and falls with constant velocity.