Test: Forces, Friction, Gravity
Terms in this set (49)
When can different forces be added together?
When they are acting on the same object, in the same direction.
Give an example of exerting a force.
Pulling a rope, pushing a wheelbarrow or punching a bag.
What happens when all forces are balanced?
No change in motion or no movement.
What must happen in order for an object to change its motion?
There must be an unbalanced force.
What must happen to make an object move?
A push or pull or unbalanced force.
What will happen to an object when the forces on it are unbalanced?
Acceleration or movement or change in motion.
What happens to the forces when two of them are acting in the same direction?
The forces add together
What is a newton?
A unit of measure for force.
Why does a nail move when hit with a hammer?
An unbalanced force is put on the nail.
What can we say about the forces on an object that is not moving?
All forces on it are balanced.
What is a force?
A push or a pull.
What units do we use to measure force?
What does the force of friction act on?
A moving object.
Name two factors that affect the amount of friction on an object.
Types of surface and how hard the surfaces push together.
Give two examples of rolling friction.
roller skates and a bike
Why would someone put sand on an icy driveway?
To increase friction.
What do we call friction by the air?
Air resistance or fluid friction
What do we call the force of one surface rubbing against another?
Why doesn't a leaf fall straight to the ground?
What kind of friction do you have on wet pavement?
What kind of friction is there on the outside of a flying airplane?
What direction does friction act on anything that is moving?
Opposite or against the direction that the object is moving.
The upward force on something that is falling is what?
What kind of friction do you have with an eraser?
What kind of friction is bike tires moving on a road?
What is air resistance?
Friction of air on a moving object or fluid friction
What is the force that pulls falling objects toward Earth?
What is the force that causes an attraction between all objects in the universe?
What do we call the amount of matter in an object?
What two factors determine the amount of gravitational force between two objects?
Distance apart and mass
What do we call the measure of the gravity on an object on the surface of a planet?
What happens to gravity as two objects get further apart?
Why does the gravity of the earth attract you more that the gravity of a house?
Earth has more mass
What is weight?
A measure of the pull of gravity by a planet or moon.
At what rate do objects accelerate in a free fall on Earth?
9.8 m/s/s or 9.8 m/s2
What is mass?
A measure of matter in an object.
Weight is the measure of what on an object?
Mass is the measure of what in an object?
The amount of matter in an object.
Forces can be added together only if they are acting on different objects.
One of the results of friction is an increase in temperature.
Fluid friction can involve either gasses or liquids.
An object is dropped from a tall building. As the object falls the upward force of air resistance becomes equal to the downward pull of gravity. When these two forces become equal in magnitude the object will_______.
Fall at a constant speed/terminal velocity.
Using a force of 50 pounds east and a force of 10 pounds west to push on an object. What is the net force on the object?
40 pounds east
The Law of Universal Gravitation states that any two objects in the universe _______.
Attract each other.
When all forces on an object are unbalanced, the object will________.
What is the speed of a bike traveling 50 km in 10 minutes?
distance= speed X time
time = distance/speed