Force, Gravity Flashcards
The force that resists the movement of one surface past another is called ————
Friction
A push or pull is called a ——
Force
Two magnets that are held together are an example of a force that (does, or does not) touch
Does not
The speed of a moving object can be changed by (balanced, unbalanced) forces.
Unbalanced
The sum of all forces acting on an object is called (balanced, net) force.
Net
Friction is mainly caused by (rough, smooth) surfaces.
Rough
The type of friction that acts on moving bicycle wheels is called (rolling, sliding) friction.
Rolling
Soil erosion by wind is an example of (helpful, harmful) friction.
Harmful
What’s the difference between balanced and unbalanced forces?
Balanced forces do not cause a change in motion. They are equal in size and opposite in direction.
Unbalanced forces always cause a change in motion. They are not equal and opposite
What is an example of a balanced force?
Two cards leaning against each other and not falling over
What is an example of an unbalanced force?
Falling from the bed, or a book falling from a table
Explain what forces are acting on a book that you are holding steady in the palm of your hand.
Then tell whether the forces are balanced or unbalanced.
Gravity, a balanced force
Describe how force and mass worked together to create motion for your vehicle.
Used a falling weight system to make the car go. The falling weight system where the force of gravity is pulling on the mass, making the vehicle move.
How did you use friction to help move your vehicle?
Used friction from the rubber band to turn the rear axle which made the vehicle move forward.
How did friction work against the movement of your vehicle?
The friction was going the opposite direction of the vehicle making the vehicle slow down
What is friction?
The force that resists the movement of one surface past another
List the 4 types of friction and an explanation of each.
Static-resists the motion of an object just as it begins to move
Rolling-resists the motion of a rolling object
Sliding-resists the motion of a sliding object
Air resistance-something that pushes by air
Name and describe the laws of motion.
First law-The law of inertia-an object at rest stays at rest, an object in motion stays in motion, unless acted upon by an unbalanced force
Second law-the acceleration of an object depends on the mass of object and the size of the net force applied
Third law-when a force is applied to an object, the object exerts an equal force in the opposite direction
What is speed?
A measure of how fast an object is moving
What is velocity?
The speed of an object in a particular direction
Give an example of the first law of motion.
A bowling ball will keep rolling until gravity and friction stops it.
Give an example of the second law of motion.
Pushing a ball
Give an example of the third law of motion.
When a rocket goes off the pad, the exhaust in the back pushes the rocket to go the opposite direction
Why is the first law of motion called the Law of Inertia?
Inertia means the tendency of an object to remain at rest or in constant motion unless a force acts upon it
How are weight and gravity related?
Weight is the effect caused by gravity. If gravity increases, so does weight.
What is acceleration?
The rate at which the velocity of a body changes with time
How can friction help people at sports?
In basketball, it allows people to change directions quickly. The friction between their shoe and the floor lets them slow down sufficiently.
What is gravity?
The force that attracts a body toward the center of the earth, or toward any other physical body having mass
What are effects of gravity on the earth and moon?
On earth, gravity keeps the air and everything around us from drifting off into space. It causes things to fall to the ground, and causes the ocean’s tides, causes hot air to rise and colder air to fall (causing wind)
On the moon, the force of gravity is much less. People would weigh much less on the moon, because the moon is smaller and there is less gravitational pull. And you could jump a lot higher on the moon than on earth.
The moon’s gravity is about (what fraction) of the gravity on earth?
About one-sixth
The amount of gravitational force depends on what?
The distance between two objects—the greater the distance, the less gravitational pull it has.
And, the mass of the two objects—the greater the mass, the stronger the gravitational pull
Which has more gravitational pull, Earth or the moon? Why?
The earth, because it has a larger mass than the moon
In what unit are forces measured?
Newtons
What is used to find the force needed to stop a moving object?
Momentum- the more momentum it has, the harder it is to stop
What is mass?
How heavy something is without gravity–the amount of matter an object has
