Science Chapter 3 Test
Newton's third law of motion
states that when one object exerts a force on a second object, the second object exerts a force on the first object that is equal in strength and in the opposite direction
net force
sum of all the forces that are acting on an object
inertia
tendency of an object to resist any change in its motion
terminal velocity
the maximum speed an object will reach when falling through a substance, such as air
opposite
Air resistance acts in the _____ direction to the motion of an object moving through air.
opposing
Air resistance is what you call an _____ force.
3.7 N/kg
An astronaut has a mass of 100 kg and has a weight of 370 N on Mars. What is the gravitational strength on Mars?
no
Are mass and weight the same thing?
There can be forces acting on the car. The forces are just balanced, so the net force is zero.
Explain whether there can be forces acting on a car that is moving in a straight line with constant speed.
When the car's velocity stops, the passenger's velocity causes them to keep moving until another force acts on them according to Newton's first law of motion.
Explain why a passenger who is not wearing a safety belt will likely hit the windshield in a head-on collision.
The acceleration of an object depends on the mass of the object as well as the force exerted. This means that if the mass is smaller, the acceleration will be greater.
Explain why an object with a smaller mass has a larger acceleration than an object with a larger mass if the same force acts on each.
66.3 kg
Find your mass if a scale on Earth reads 650 N when you stand on it.
rolling
Friction between the tire of a moving car and they dry pavement is _____ friction.
a = Fnet/m
How can Newton's second law of motion be written?
by looking at the planets
How did Isaac Newton study most science?
It will move the direction you push it because the forces are unbalanced.
How will a box move with sliding friction?
It will not move because it balanced the applied force.
How will a box move with static friction?
lost; transferred
Momentum is never _____. It is only _____.
735 N
On Earth, what is the weight of a large-screen TV that has a mass of 75 kg?
weight
The _____ of an object is different on every planet in the solar system.
gravity
The attractive force between two objects that depends on their masses and the distance between them is _____.
greater
The greater an object's mass is, the _____ its inertia is.
50 N
Two students push on a box in the same direction, and one student pushes in the opposite direction. What is the net force on the box if each student pushes with a force of 50 N?
friction between the tires and the road
What acts as a centripetal force when a car rounds a level curve on a highway?
gravity, electromagnetic force, strong nuclear force, weak nuclear force
What are the four basic forces?
their masses
What causes a softball and a baseball to travel at different velocities?
microwelds forming and reforming
What causes friction?
heat
What do surfaces rubbing together create?
free fall
describes the fall of an object on which only the force of gravity is acting
air resistance
force that opposes the motion of objects that move through the air
friction
force that opposes the sliding motion between two touching surfaces
weight
gravitational force exerted on an object
The net force of a car slowing down is opposite the direction of its motion. This is because rolling friction is greater than the car's force.
Determine the direction of the net force on a car if it is slowing down. Explain.
The inertia of an object does not change. The only time the inertia changes is when the object changes mass.
Determine whether the inertia of an object changes as the object's velocity changes.
gravity
Acceleration due to gravity is equal to the strength of _____.
40.8 kg
A boy weights 400 N. What is his mass?
1500 kg
A car pulled by a tow truck has an acceleration of 2 m/s² east. What is the mass of the car if the net force on the car is 3,000 N east?
4.9 N
A squirrel has a mass of 0.5 kg. What is its weight?
2 m/s²
A student pushes on a 5 kg box with a force of 20 N forward. The force of sliding friction is 10 N backward. What is the acceleration of the box?
centripetal force
a force that is directed toward the center of a curved or circular path
smaller surface area
If a bag has a _____, it will fall faster because of air resistance.
4 m/s² upward
If a helicopter's mass is 4,500 kg and the net force on it is 18,000 N upward, what is its acceleration?
grease
What do you have to use on surfaces to make them move smoothly?
1 kg∙m/s²; m/s²
What does 1 N equal to? Because of this, what unit can g also be written in?
size, shape, mass
What does an object's terminal velocity depend on?
some kind of force
What does everything have acting on it?
size, shape, and speed of the object
What does the amount of air resistance on an object depend on?
Gravitational force increases as the mass increases or as the objects move closer.
What does the law of universal gravitation state?
gravity
What does weight use that mass does not?
The tires will slide instead of gripping the ground.
What happens when the force to rotate the tires on a car is larger than the force of static friction between the wheels and the ground?
the law of inertia
What is Newton's first law of motion also known as?
To every action, there is an equal and opposite reaction.
What is another way you can phrase Newton's third law of motion?
force
What is gravity an example of?
terminal velocity
What is it called when acceleration on a falling object is zero?
wheels
What is one item that would not work without friction?
It is when static friction acts over the area where the wheel and surface are in contact.
What is rolling friction?
It is a type of friction that opposes the motion of two surfaces sliding past each other and is caused by microwelds constantly breaking and forming as the objects slide past each other.
What is sliding friction?
It is a type of friction that prevents two surfaces from sliding past each other and is due to the microwelds that have formed between the bottom of the object and the floor.
What is static friction?
mass
What is the amount of matter in an object?
W = mg
What is the equation for weight?
D
What is the gravitational force exerted on an object called? A. centripetal force B. friction C. momentum D. weight
9.8 N/kg
What is the gravitational force on Earth?
28,800 N west
What is the net force on a dragster with a mass of 900 kg if its acceleration is 32 m/s² west?
0; there is no acceleration
What is the net force on a sky diver falling with a constant velocity of 10 m/s downward?
the object's mass
What is the object's inertia related to?
balanced force
What kind of force is present when the forces exerted on the object are equal?
unbalanced force
What kind of force is present when the forces exerted on the object are not equal, causing the object to move?
newtons
What unit is weight given in?
centripetal force
When an object moves in a circular path, the net force is called a _____.
weightlessness
When you are in free fall, you are said to have a feeling of _____.
B
Which body exerts the strongest gravitational force on you? A. the Moon B. Earth C. the Sun D. this book
B
Which explains why astronauts seem weightless in orbit? A. Earth's gravity is much less in orbit. B. The spacecraft is in free fall. C. The gravity of Earth and the Sun cancel. D. The centripetal force on the shuttle balanced Earth's gravity.
sliding friction
Which force is usually smaller: sliding friction or static friction?
C
Which of the following is not a force? A. weight B. friction C. momentum D. air resistance
C
Which of the following is true about an object in free fall? A. Its acceleration depends on its mass. B. It has no inertia. C. It pulls on Earth, and Earth pulls on it. D. Its momentum is constant.
gravity, electromagnetic force
Which of the four basic forces have infinite range?
rough surfaces
Which surfaces creates more friction: rough surfaces or smooth surfaces?
A
Which term best describes the forces on an object with a net force of zero? A. balanced forces B. unbalanced forces C. inertia D. acceleration
B
Which term describes the tendency of an object to resist a change in motion? A. balanced force B. inertia C. net force D. acceleration
Isaac Newton
Who created the law of universal gravitation?
air resistance
Why does a feather fall slower than a billiard ball?
2 kg
You push yourself on a skateboard with a force of 30 N east and accelerate at 0.5 m/s² east. Find the mass of the skateboard if your mass is 58 kg.
Friction
_____ opposes the sliding motion of two surfaces that are in contact.
Newton's second law of motion
_____ relates the net force exerted on an object to its mass and acceleration.
force
a push or pull exerted on an object
field
a region of space in which every point has a physical quantity, such as a force
gravity
attractive force between two objects that depends on the masses of the objects and the distance between them
Newton's first law of motion
states that an object moving at a constant velocity keeps moving at that velocity unless an unbalanced force acts on it
law of conservation of momentum
states that if no external forces act on a group of objects, their total momentum does not change
Newton's second law of motion
states that the acceleration of an object is in the same direction as the net force on the object, and that the acceleration equals the net force divided by its mass
A
An object always accelerates in the same direction as which of the following? A. net force B. air resistance C. static friction D. gravity
centripetal force
Anything that moves in a circle is doing so because a _____ is accelerating it toward the center.
increases
As an object falls faster, the upward force of air resistance _____.
no
Does the gravitational force between two object ever come to absolute zero?
the same
If there were no air resistance, then all objects would fall with (different/the same) acceleration.
the same
If two objects have different masses, they will feel (a different/the same) amount of force.
ok
Look at number 39 on page 98 in the book.
ok
Look at number 55 on page 99 in the book.
ok
Look at numbers 44-46 on page 99 in the book.