Gravity The force of attraction between objects that is due to their masses The force of attraction between objects that is due to their masses All matter has mass, so all matter experiences gravity. All matter has mass, so all matter experiences gravity. esandtime/gravity/ esandtime/gravity/ esandtime/gravity/ esandtime/gravity/

The Law of Universal Gravitation Stated by Sir Isaac Newton ( ) Stated by Sir Isaac Newton ( ) “All objects in the universe attract each other through gravitational force. The size of the force depends on the masses of the objects and the distance between them.” “All objects in the universe attract each other through gravitational force. The size of the force depends on the masses of the objects and the distance between them.”

Mass vs. Weight Mass is the amount of matter in an object. Mass is the amount of matter in an object. (Measured in grams or kilograms) Weight is the measure of the gravitational force exerted on an object. Weight is the measure of the gravitational force exerted on an object. (Measured in Newton's) (Measured in Newton's) Why do we weight less on the moon? Why do we weight less on the moon? -Because the moon has less mass than the earth. earth.

Galileo proposed that all object s will land at the same time when they are dropped from the same height. Galileo proposed that all object s will land at the same time when they are dropped from the same height. Mass of an object does not affect the rate at which it falls. Mass of an object does not affect the rate at which it falls. Objects fall to the ground at he same rate because the acceleration due to gravity is the same for all objects. 9.8 m/s/s constant rate Objects fall to the ground at he same rate because the acceleration due to gravity is the same for all objects. 9.8 m/s/s constant rate Equation: V = g x t Equation: V = g x t

Acceleration due to gravity 9.8 m/s/s – the rate at which all objects fall towards earth (ignoring air resistance.) 9.8 m/s/s – the rate at which all objects fall towards earth (ignoring air resistance.)

Math Break To find the change in velocity (ΔV) of a falling object, multiply the acceleration due to gravity (g) by the time it takes for the object to fall in seconds (t). The equation for finding a change in velocity is as follows: To find the change in velocity (ΔV) of a falling object, multiply the acceleration due to gravity (g) by the time it takes for the object to fall in seconds (t). The equation for finding a change in velocity is as follows: ΔV = g x t For example, a stone at rest is dropped from a cliff, and it takes 3 seconds to hit the ground. Its downward velocity when it hits the ground is as follows: ΔV = 9.8 ­­m/s x 3 s S = 29.4 m /s = 29.4 m /s

Terminal Velocity Is the point at which a falling object stops accelerating and begins to fall at a constant speed. Is the point at which a falling object stops accelerating and begins to fall at a constant speed. If there were no atmosphere there would be no air resistance. (That’s why a feather and a rock would land at the same time if dropped on the moon.) If there were no atmosphere there would be no air resistance. (That’s why a feather and a rock would land at the same time if dropped on the moon.)

Parachute lab Skydivers are people who jumped out of airplanes and live to write about their experiences. They used parachutes to slow their fall in order to land safely

Question Does the mass affect the falling velocity with a parachute? Does the mass affect the falling velocity with a parachute?

How a parachute works Introduction: When an object is dropped, the force of gravity will cause it to speed up as it falls. But friction with the air, called drag, will tend to cause it to slow down. How much drag there is depends mostly on two factors: When an object is dropped, the force of gravity will cause it to speed up as it falls. But friction with the air, called drag, will tend to cause it to slow down. How much drag there is depends mostly on two factors: Speed: The faster an object moves through air the more drag there is. Speed: The faster an object moves through air the more drag there is. Shape: A compact object with smooth surfaces experiences less drag than an object of the same mass that is spread out and rough. Shape: A compact object with smooth surfaces experiences less drag than an object of the same mass that is spread out and rough.

As a falling object speeds up, drag increases until it is equal to gravity. At that point, the object continues to fall at a constant speed, called terminal velocity. With an open parachute, the shape of the falling mass is changed and spread out so that drag is much greater. The balance between gravity and drag occurs at a lower speed, a lower terminal velocity. As a falling object speeds up, drag increases until it is equal to gravity. At that point, the object continues to fall at a constant speed, called terminal velocity. With an open parachute, the shape of the falling mass is changed and spread out so that drag is much greater. The balance between gravity and drag occurs at a lower speed, a lower terminal velocity.

Hypothesis I think that a heavier object will fall faster because blah blah blah… I think that a heavier object will fall faster because blah blah blah… I think a parachute will not affect the rate blah blah blah. I think a parachute will not affect the rate blah blah blah.Procedure: Write at least 7 steps to build a parachute and to test two different mass at a standard height. Record the velocity. Write at least 7 steps to build a parachute and to test two different mass at a standard height. Record the velocity. Include sketches of design. Include sketches of design.

Data ( Record) velocity at three different masses ( Record) velocity at three different masses Then record velocity of heaviest mass with higher height and wind. Then record velocity of heaviest mass with higher height and wind.Conclusion: What your hypothesis supported? What mass had the greater velocity? How did fluid friction affect the velocity? Did the parachute size matter? Compared to others results how did you compare? What your hypothesis supported? What mass had the greater velocity? How did fluid friction affect the velocity? Did the parachute size matter? Compared to others results how did you compare?

Purpose Design a better parachute, but you have to decide first what "better" means. a parachute that brings your test object (egg or water balloon) down more slowly. a parachute that brings your test object (egg or water balloon) down more slowly. The lightest parachute possible The lightest parachute possible Strength and durability? (can test many time with same results/Parachute doesn’t break easily) Strength and durability? (can test many time with same results/Parachute doesn’t break easily) The trial with the longest time and keeps the egg safe wins! The trial with the longest time and keeps the egg safe wins!