FORCES Lesson 1 Gravity

MAIN IDEA: HOW DOES GRAVITY AFFECT OBJECTS? D1: Earth’s gravity pulls all objects on Earth toward Earth’s center. D2: Gravitational force is the force of attraction between any object and every other object in the universe.

D3: Gravity depends on the masses of the two objects that exert gravitational forces on each other. The greater the mass of an object, the stronger its gravitational force. D4: Gravitational force depends on the distance between two objects. If the distance between objects increases, the gravitational pull between them decreases.

D5: Gravitational force becomes larger as objects move closer to each other.

WEIGHT VS MASS (P. ______) Amount of matter in an object. What is the difference? Weight: Is the gravitational force exerted on an object. Your weight is actually a force measured in Newton’s. Demonstration: Mass & Gravity LINK

Gravity and Air Resistance Most objects falling through air experience a type of fluid friction called air resistance. Air resistance is not the same for all objects. The greater the surface area of the object the greater the air resistance. (paper drop) However, since the elephant has more mass, it has more downward force of gravity and falls faster.

Gravity and Free Fall Take away ALL air, so that only the force of Gravity is being used. An object is in free fall when the only force acting on the object is gravity. Free-falling objects do not encounter air resistance. In free fall, the force of gravity is an unbalanced force. Gravity Tube Demonstration TRY THIS

MAIN IDEA: HOW DO YOU MEASURE EARTH’S GRAVITATIONAL PULL? D1: To find Earth’s gravitational force just weigh yourself. D2: An object’s mass- the amount of matter that makes up the object- is the same everywhere in the universe. D3: Weight depends on your location. D4: You weigh more on Earth than on the moon. D5: Like all forces, weight can be measured in Newtons.

Universal Gravitation The law of universal gravitation states that the force of gravity acts between all objects in the universe.