Name:______date:______period:______(3)

Science 8: Ch 13.2 Gravity and Motion (pages 376-383)

Key Concept
Gravity can be an ______force that causes ______changes in ______.
Why would Aristotle think a baseball would fall faster than a marble?
Did Galileo Galilei agree with Aristotle?
How might have Galilei tested his idea that mass does not affect the rate at which an object falls?
What do objects fall at the same rate?
What does acceleration depend on?
Which has a greater gravitational force, a heavier or lighter object?
Which has a harder time accelerating, a heavier or lighter object?
The extra mass of a heavy object exactly makes up for what?
Acceleration is the rate at which velocity changes over what?
An object accelerates when the forces on it are which, balanced or unbalanced?
What does gravity exert on all falling objects?
Do objects accelerate as they fall?
At what rate to objects fall?
What happens every second something falls?
What is the equation for calculating the change in velocity for a falling object?
In the equation for calculating the change in velocity for a falling object, what does g stand for?
In the equation for calculating the change in velocity for a falling object, what does t stand for?
The change in velocity is the difference of what?
What happens when a flat sheet of paper and a crumpled sheet of paper fall at the same height?
Which falls at a slower rate?
Why does it fall at a slower rate?
Define air resistance
Air resistance on an object depends on what? / 1.
2.
3.
Why does air resistance act more on the flat sheet of paper?
How do you determine the net force of a falling object? (Figure 3 on page 378)
As the speed of a falling object increases, what also increases?
What happens when the net force of a falling object is 0 N?
What type of velocity happens at constant velocity?
What would happen to hailstones if no air resistance was present?
Are sky divers really in free fall?
Define free fall
Where could an object be in free fall?
Define vacuum.
Looking at Figure 4, in a vacuum, what objects will drop at the same rate?
What is an example of projectile motion?
Define projectile motion
How many movements are in projectile motion?
Are the movements separate?
Do movements have any effect on each other?
When the two movements are put together, what kind of path is formed?

Looking at Figure 5, show how projectile motion forms a curve.

What are two other examples of projectile motion? / 1.
2.
When you throw a ball to a friend, what produces movement parallel to the ground?
When the ball leaves your hand, does gravity affect the horizontal movement of projectile motion?
Gravity gives the ball what type of movement?
If air resistance is ignored, gravity pulls the ball in projectile motion at what acceleration?
Because objects in projectile motion accelerate down, what do you need to do to hit a target like a bulls eye?
What is an object doing when it is moving around another object in space?
What direction is a spacecraft moving when orbiting Earth?
Why is a spacecraft orbiting Earth also in free fall?
What path does a spacecraft take if in orbit? (Figure 7)
The paths of an object in orbit are not circular (after a full rotation) but what shape?
What unbalanced force is acting on the elliptical path of an object in orbit?
Gravity provides what type of force that keeps things in orbit?
Gravity between the planets and the sun keeps planets in orbit around what?
Just like the gravity between the moon and Earth keep the moon rotating around Earth, is this similar to the gravity causing the rings of ice and dust to orbit Saturn?