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Chapter 3
DHS PS Ch. 3 - Forces (Online Course)
Question | Answer |
---|---|
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 |