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# Chapter 3

### DHS PS Ch. 3 - Forces (Online Course)

What happens to the gravitational force as objects get farther apart? It decreases rapidly but never gets to zero
You exert a gravitational force on _________. everything
How does weight relate to mass? Weight is mass times acceleration due to gravity.
What causes thrown objects to travel in a curved path? Earth's gravitational pull and the inertia of the object
What happens to the amount of gravity a projectile experiences as it moves through the air? It remains constant
What provides centripetal force when a car experiences centripetal acceleration around a corner? friction between the tires and road
In which direction is the centripital force? toward the center of the circle
Astronauts "float" when inside an orbiting spaceship because they are _______________ in free fall.
Newton's third law of motion states that ____________. for every action force there is an equal and opposite reaction force that occurs at the same exact time.
What causes a rocket to move ? The rocket's engines exert a force on exhaust gases and the gases exert a force back on the rocket.
If two objects with different masses and traveling with different velocities collide, what law allows you to predict the motion of the objects after the collision? the law of conservation of momentum
Whenever a force is exerted, another force occurs that is ______ in size, and ________ in direction. equal, opposite
Action-reaction force pairs never __________? act on the same object.
An object will have zero momentum if ________. it has zero velocity or zero mass
What is the reaction force when you place a cup on a table? the force of the table back up on the cup
When a falling object reaches terminal velocity, the force of gravity ___________ the force of air resistance. is equal and opposite to.
When force is increased on an object, what happens to its acceleration? It increases.
When gravitational forces and air resistance equalize on an object that is falling toward Earth and the object stops accelerating, what is the velocity of an object called? terminal velocity
Name 3 benefits to friction. It allows objects to start, stop, or turn.
All objects fall at a constant rate of 9.8 m/s2 unless you factor in _________ air resistance.
Which of the following will result in the greatest acceleration? The greatest force acting on the smallest mass.
Newton's second law of motion is ____________? an object will accelerate in the direction of an applied force, depending on the object's mass.
Static friction occurs when two objects are _______________. at rest
The upward force on an object falling through the air is _______________. air resistance
The relationship among mass, force, and acceleration is explained by ________________. Newton's second law of motion
A feather will fall through the air more slowly than a brick because of _____________. air resistance
In a vacuum, an apple and a feather that are dropped from the same height at the same time will ___________________. fall at the same rate
The acceleration due to gravity near the Earth's surface is always _____________. 9.8 m/s2
According to Newton's second law of motion, ______________________. F = ma
The path of a projectile is _______________. always 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 surface of Earth, your 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 ____________________. action-reaction
A real car moving at 10km/h has more momentum than a toy car moving at the same speed because the real car _________________. has greater mass
In the equation p = m x v, the p represents ___________________. momentum
The statement "to every action there is an equal and opposite reaction" is _____________. Newton's third law of motion
Momentum is measured in what units? kg x m/s
When two objects collide, the momentum of the balls after the collision is explained by ______________________. the law of 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 _________________________. continue to travel horizontally
The motion of an object parallel to Earth's surface is _______________________. horizontal
If a 500-N action force is exerted to the right, the reaction force will be ________________________. 500 N to the left
Friction between the tire of a moving car and the dry pavement is ____________ friction. rolling
Gravity is one of ____________ basic forces. four
What exerts the strongest gravitational force on you? Earth
What happens immediately after a sky diver opens her parachute? Air resistance greatly increases.
Which object has the greatest inertia between a bowling ball, tennis ball, and a beach ball? a bowling ball (it has the most mass)
If a greater force is applied to Car A compared to Car B, Car A will have _______________ acceleration as (than) Car B. greater
How does weight relate to mass? Weight is mass times acceleration due to gravity.
Force and motion are ______________________. connected
When a force is applied to an object, the _________ of an object will affect acceleration. mass
Newton's second law of motion states that acceleration is equal to force _____________ by mass. divided
If two surfaces are touching each other, what force opposes the motion between them? friction
What is the ultimate source of friction where surface bumpers stick together? microwelds
Which type of friction occurs between two surfaces that are not moving past each other? static
The force that opposes the motion of two surfaces sliding past each other is called _____________ friction. sliding
When a force occurs between a rolling object and the surface it rolls on, it is known as ____________________ friction. rolling
What opposes the motion of objects that move through the air? air resistance
An object's size, shape, and speed depend on the _____________ of air resistance. amount
Is gravity a ______ _______ force that gives the universe its structure? long-range
The four basic forces include electromagnetic force, strong nuclear force, weak nuclear force, and ___________________. gravity
Regardless of mass, all objects fall with the same acceleration due to __________________. inertia
What is the gravitational force exerted on an object called? weight
If weight results from a force, then _________ is a measure of how much matter an object contains. mass
What do objects in the space shuttle do when they have no force supporting them? float
When an object accelerates toward the center of a curved path _____________ acceleration occurs which is caused by centripital ____________. centripital, force
Newton's third law of motion states that to every action force there is an equal and ___________________ reaction force. opposite
Rocket propulsion is based on ______________? Newton's third law of motion
Action-reaction forces differ from balanced forced as they act on different or identical objects? different
What is related to how much force is needed to change an object's motion? momentum
The law of conservation of momentum states that momentum can be __________________ between objects; momentum is not lost or gained in the transfer. transferred
Two objects have the same mass. Object A is motionless. Object B is traveling at 2 m/s. After they collide, the stick together and move as one unit. What is their resultant velocity? 1 m/s since the mass is doubled (the velocity is now half)
Which law explains why a motorcycle will always beat a car if they both produce the same amount of force? Newton's 2nd law
Which law explains why once a satellite is put in motion, it will continue to stay in motion? Newton's 1st law
Which law explains why when a canon fires a canon ball, the canon ball goes one direction while the canon goes the opposite? Newton's 3rd law
Which law allows you to predict the motion of objects after a collision? Law of conservation of momentum
Where did Isaac Newton attend college? Cambridge University in Britain
Why did Newton's college close down for 18 months in 1665? Because of the bubonic plague
You can only add forces together when they are _________ ? in the same direction
You must subtract forces when they are __________ ? in opposite directions.
If two object are twice as far apart, the gravitational force between them is now _____ as strong. half
If two object are 3x as far apart, the gravitational force between them is now _____ as strong. 1/9th
If two object are 4x as far apart, the gravitational force between them is now _____ as strong. 1/16th
If two object are 10x as far apart, the gravitational force between them is now _____ as strong. 1/100th
Weight is measure in _______ . Newtons
Gravitational strength is measure in _______ . N/kg
The gravitational force on the moon is ______ as strong as the Earth's. 1/6th
Newton's first law of motion is also known as the law of _____ . inertia
These work in a car crash to keep a passenger from being thrown out as well as decreasing the amount of force experienced. Seat belts
Air bags inflate using a chemical reaction that produces _______ . nitrogen gas
Created by: basmith