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Chapter 3- Forces

8th Grade Science

What is any push or pull on an object? Force
What is the force that opposes motion between two surfaces in contact with each other? Friction
What is the force exerted by air on a moving object? Air Resistance
What type of friction is between two surfaces that are not moving past each other? Static Friction
What type of friction is between the wheels of a car in motion and the road? Rolling Friction
What is the largest velocity that is reached by a falling object when the force of air resistance equals the force of gravity? Terminal velocity
What is the force that every object in the universe exerts on every other object? Gravity
What is the pull of gravity on an object? Weight
What is the amount of matter in an object? Mass
What is it called when gravity is the only force acting on a falling object (no air resistance)? Free Fall
What is the force that keeps an object moving in a circle? Centripetal Force
What type of acceleration does a space shuttle in orbit have due to gravity and inertia? Centripetal Acceleration
What is anything thrown or shot through the air called? Projectile
What is the path of a projectile called? Trajectory
What is the property of a moving object resulting from its mass and velocity? Momentum
What is the force that keeps the moon in orbit around the earth? Gravity
How is the relationship among mass, force and acceleration explained? Newton's second law of motion
What causes a piece of paper to fall through the air more slowly than a boulder? Air resistance
In absence of air, a penny and a feather that are dropped from the same height at the same time will___. fall at the same rate
When an object moves in a circular path, it accelerates toward the center of the circle as a result of___. Centripetal Force
The path of a projectile is ___. Curved
For any object, the greater the force that's applied to it, the greater its ___ will be. Acceleration
The size of the gravitational force between two objects depends on their ___. masses and the distance between them
As you get farther from the center of the Earth, you weight will ___. Decrease
When a force is exerted on a box, an equal and opposite force is exerted by the box. These forces are called ___ forces. Action-reaction
What kind of friction occurs when a person slams on their brakes and the car skids to a stop? Sliding friction
What does p represent in the equation p=m*v? Momentum
What is Newton's Third Law of Motion? To every action there is an equal and opposite reaction
What is the unit for momentum? kg* m/s
When two balls collide, the momentum of the balls after the collision is explained by __. The law of the conservation of momentum
An object that is in free fall seems to be ____. Weightless
If gravity did NOT affect the path of a horizontally thrown ball, the ball would ___. Travel horizontally
Because of projectile motion, when aiming at a target you should always aim ____. Above the bull's eye
What causes friction? Friction is caused by microwelds
A book and a piece of paper, the same size, fall at different rates. How can you change the shape of the paper so it will fall at nearly the same rate as the book? The paper can be changed by crumbling it into a ball. It has less air resistance this way.
Explain how mass and weight are measured differently in science. Mass is measured in grams on a balance while weight is measured in Newtons with a spring scale.
Explain the action-reaction forces of a rocket in space. The rocket pushes gases and the gases push the rocket.
Sally throws a ball horizontally from the top of a tall building at the same time Pete drops a ball from the top of the same building. Which ball will hit the ground first? Both of the balls will have the same gravity acceleration so they will hit at the same time.
Created by: katiesmith