Physics Chapter 2

what is the magnitude of a unit vector A.) 0 B.) Direction C.) 1

1

The two ways of specifying a vector are by its magnitude and direction, or by specifying each of its three ______

Components

A vector can be written as _____ , which are parts of the vector along different ____ .

Components and axes

Select the correct statement.

Contact forces only apply while the two objects are in contact

Which fundamental forces have the longest range? The weak force Gravity The strong force Electomagnetism

Electomagnetism and Gravity

Select all of the following that are vectors A.) Force B.) Temperature C.) Velocity D.) Time E.) Mass

Force and Velocity

A car moving to the right is sliding to a halt. Select the correct description of the force of friction. A.) Static friction to the right B.) Static friction to the left C.) Kinetic friction to the left D.) Kinetic friction to the right

Kinetic friction to the left

You push on a 20 kg box that is lying on a horizontal surface with a 150 N horizontal force. The coefficient of static friction is 0.8. What can you say about the resulting motion of the box?

The box will not move

Which fundamental force has the shortest range? The weak force Gravity The strong force Electomagnetism

The weak force

Select all statements that are true. The weight of an ideal pulley is always zero. Ideal pulleys change the direction of the force of tension, but not its magnitude. Ideal pulleys change both the direction of the force of tension and its magnitude. The mass of an ideal pulley is always zero. Ideal pulleys change the magnitude of the force of tension, but not its direction.

The weight of an ideal pulley is always zero Ideal pulleys change the direction of the force of tension, but not its magnitude The mass of an ideal pulley is always zero

How many forces are needed to describe and measure an interaction between two objects? A.) Three B.) Four C.) Two D.) One

Two

Which of the following equations correctly relates the weight W of an object to its mass m? A.) W= m/g B.) W=mg C.) W=m

W=mg

In which situations do contact forces apply?

only when the objects are touching

A crate with a child sitting on top of it is being pulled to the right with a force F→ across a horizontal floor. Both the child and the crate are moving to the right at a constant speed. For each of the forces in the left column, match the object upon which its interaction partner acts 1. )Gravitational force on the child = 2.) Contact force on the child = 3.) Contact force on the top surface of the crate = 4.) Contact force on the bottom surface of the crate =

1.) Earth 2.) Crate 3.) Child 4.) Floor

Select all of the following that could be properties of scalars A.) Algebraic sign B.) Magnitude C.) Units D.) Direction

Algebraic sign Magnitude Units

A bucket of water has two forces acting on it. The upward force is called tension, and the downward force is called gravity. If the bucket of water is being raised from a well at a constant velocity, then the magnitude of the tension is greater than the magnitude of the force of gravity true or false

False

A temperature of -5 degrees Celsius is not a scalar because it is negative. True or false:

False

Forces can only be measured by springs. True or False

False

The property of an object to resist changes in velocity is called ______

Inertia

A heavy crate of mass M is being lifted up at a constant speed by applying a force F→ , as shown. Which rope has the least amount of tension? Assume that the pulleys and ropes are ideal. Rope 1, 2, or 3

Rope 2

A box weighing 400 N lying on a horizontal surface is pushed by a 200 N horizontal force. The box is just on the point of slipping. What is the coefficient of static friction? A.) There is not enough information to answer the question B.) equal to 0.5 C.) Greater than 0.5 D.) Greater than zero but less than 0.5

equal to 0.5

A toolbox sits on the bed of a truck that is initially at rest. The truck starts to move to the right, and the toolbox does not slide toward the back of the truck. It remains at rest with respect to the bed of the truck. Select the correct description of the force of friction.

static friction to the right

Select all of the following sums that are equal to (5 N, 30 degrees north of east) A.) (4 N, east) and (4 N, north) B.) (4.33 N, east) and (2.5 N north) C.) (1 N, north) and (5 N, west) D.) (1 N, west, (5.33 N, east) and (2.5 N, north)

(4.33 N, east) and (2.5 N north) and (1 N, west, (5.33 N, east) and (2.5 N, north) NOTES: A.) The direction of this sum is northeast (exactly halfway between north and east). C.) The direction of this sum is between north and west

A car is driving on a level highway. It is acted upon by the following forces: a downward gravitational force of 12 kN, an upward contact force due to the road of 12 kN, another contact force due to the road of 7 kN directed West, and a drag force due to air resistance of 5 kN directed East. What is the net force acting on the car?

2kN

The system shown in the figure is in equilibrium. Rank the three ropes according to the magnitude of the force of tension, from greatest at the top to smallest at the bottom Rope 3,2,1

321

Select all of the following that are vectors A.) 90N, UP B.) 90N C.) North by Northwest D.) 90N, north

90N, Up 90N, north

Select all of the following forces that are contact forces. A.) A foot kicking a ball B.) Electric forces C.) Gravitational forces D.) A rope pulling a box E.) Magnetic forces

A foot kicking a ball A rope pulling a box

Select the correct statement. A.) Long-Range forces always apply B.) Long-range forces only apply when the two objects have never been in contact C.) Long-range forces only apply when the two objects used to be in contact but are no longer in contact D.) Long- range forces only apply when the two objects have always been in contact

Long-Range forces always apply

A box on a rough surface is sliding at a constant velocity, so you know the net force acting on it is zero. There is a force F to the right applied by a person and a friction force f to the left applied by the ground. Select the interaction pair to the friction force f applied by the ground. A.) The force applied by the person to the box to the right B.) The force applied by the box on the person to the left C.) The friction applied by the box on the ground to the right

The friction applied by the box on the ground to the right

Select all of the following that are properties of all vectors. A.) Magnitude B.) Distance C.) Direction D.) Length

Magnitude and Direction

The sum of external forces on a system ALWAYS equal to what? A.) The net force on the system B.) Zero C.) Sum of the internal forces

The net force on the system

The sum of the internal forces on a system always equal to what? A.) zero B.) the net force on the system C.) The sum of external forces

ZERO The sum of the external forces is always equal to the net force on the system. Only when the sum of the external forces is equal to zero are the sums of the internal and external forces equal. Only when the sum of the external forces is equal to zero are the sums of the internal and external forces equal

Which of the following are unit vectors? A.) x,y,z B.) X-axis, y-axis, z-axis C.) ^x, ^y,^z

^x, ^y,^z

Select all the situations below that imply there is no net force acting on the object A.) A rock sitting on the ground B.) A ball rolls straight along smooth, level ground with constant speed C.) A balloon ascends straight up with constant speed D.) A couple rides a merry go round with constant speed E.) A child on a tricycle turns a corner with constant speed F.) A rock falls straight down off a ledge, picking up speed

A rock sitting on the ground A ball rolls straight along smooth, level ground with constant speed A balloon ascends straight up with constant speed D.The velocity vector is changing because the direction is changing. A net force is required to change the velocity vector. E. The velocity vector is changing because the direction is changing. A net force is required to change the velocity vector. F. The velocity vector is changing because the magnitude is increasing. A net force is required to change the velocity vector.

Select all of the following that are parts of vector components. A.) Algebraic sign B.) Angle C.) Units D.) Magnitude

Algebraic sign Units Magnitudes

Select all of the following forces that are long-range forces A.) Gravitational Forces B.) Contact forces C.) Magnetic forces D.) Electric forces

Gravitational Forces Magnetic Forces Electric Forces

An object is moving to the right at a constant velocity. Which of the following statements is correct? A.) The net force acting on the object is to the left B.) The net force is acting on the object on the object to the right C.) The net force acting on the object is zero D.) The net force acting on the object is to the right

The net force acting on the object is zero

Consider two objects, one with a great deal of inertia and one with very little. Select the correct statements A.) The object with a great deal of inertia is easier to start moving from rest B.) The object with a great deal of inertia is easier to stop when it is in motion C.) The object with a great deal of inertia is moving faster than the object with very little inertia D.) The object with very little inertia is easier to start moving from rest E.) The object with very little inertia is easier to stop when it is in motion

The object with very little inertia is easier to start moving from rest The object with very little inertia is easier to stop when it is in motion

What is G in the equation F = G m1m2r2 ? A.) The magnitude of the acceleration due to gravity on the surface of m1 B.) 9.8 m/s^2 C.) The universal gravitational constant D.) The magnitude of the acceleration due to gravity on the surface of m2

The universal gravitational constant

Select all of the following properties of coordinate axes that are required A.) One must be horizontal, and the other must be vertical B.) They must be perpendicular to each other C.) They cannot be parallel to each other D.) They must lie in the horizontal plane

They must be perpendicular to each other They cannot be parallel to each other

Select all the situations below that will lead to an object having a constant velocity A.) Two equal forces act on the object in opposite directions B.) No forces act on the object C.) Two equal forces act on the object in the same direction D.) Only one force acts on the object C.) Three forces acting on an object, which altogether sum to zero

Three forces acting on an object, which altogether sum to zero No forces act on the object Two equal forces act on the object in opposite directions

Select all of the following statements that are true A.) Force is he same as energy B.) Two forces can describe the interaction between two objects C.) A force is a push or pull D.) Once force can describe the interaction between two objects

Two forces can describe the interaction between two objects and A force is a push or pull

Rank the following pairs of force according to the magnitude of the net force, with the largest magnitude net force at the top and the smallest at the bottom. A.) (5 N, right) and (3 N, right) B.) (7 N, right) and 8 N, left) C.) (9 N, left) and (6 N, right) D.) (9 N, right) and (9 N, left)

A, C, B, D A = 8N right (5N+3N) B = 1N left (7N-8N) C = 3N left (9N-6N) D = 0 (9-9)

Rank the following pairs of force according to the magnitude of the net force, with the largest magnitude net force at the top and the smallest at the bottom. A.) (4.0 N left,) and (4.0 N, up) B.) (4.0 N, right) and (4.0 N, left) C.) (4.0 N,right) and (4.0 N,right)

A.) sqaure root 4^2+4^2 = 5.66 N B.) 4-4 =0 C.) 4+4 = 8

Two boxes, A and B, are suspended from a ceiling, as shown. Select all of the following forces that must be included in the free-body diagram of box A. A.) Gravity caused by the Earth B.) Force caused by rope 2 C.) Gravity caused by A on the earth D.) Force caused by rope 1

Gravity caused by the Earth Force caused by rope 2 Force caused by rope 1

What is the unit of force in the SI system? A.) Newton B.) Ounce C.) Kilogram D.) Pound

Newton

The net force acting on an object is zero. Select the correct statement. a. there are no forces acting on the object b. all forces acting on the object must be equal c. the object can not change its direction of motion d. the object must be at rest

the object can not change its direction of motion a. There can be individual forces acting on the object, but they must all be in balance together so as to cancel out. b.If the forces were equal, then they would have the same magnitude and direction. If they were in the same direction, they could not cancel one another d. If the net force equals zero, then the velocity vector must be constant. It can still be in motion, but it can't change speed or direction

In the figure, an airport luggage carrying train with a tractor T is pulling three luggage carts, M1, M2, and M3 with constant velocity of 4.5 m/s. If T = 300 kg, M1= 200 kg, M2 = 100 kg, and M3 = 100 kg (there is no friction), then the force in the connection between the tractor T and cart M1 is

0.00N

Rank the following according to the magnitude of the gravitational force, with the smallest magnitude at the top and the largest at the bottom. Assume that the distance between the centers of the two masses is constant

1.) m^1=5m,m^2=5m 2.) m^1=8m,m^2=6m 3.)m^1=5m,m^2=10m 4.)m^1=7m,m^2=8m

Rank the following according to the magnitude of the gravitational force, with the smallest magnitude at the top and the largest at the bottom. Assume that the two masses are constant r=4Rr=2Rr=R)

1.)r=4R 2.)r=2R 3.)r=R)

During a mission training session at the Kennedy Space Center in Florida, one of the Apollo mission astronauts measures his mass to be 72 kg. Assume the magnitude of the earth's gravitational field to be 10 m/s2 and the magnitude of the moon's gravitational field to be 1/6 of that of the earth. Select all of the following statements that are true A.) His weight on the moon is zero B.) His mass on the moon is zero C.) His weight on the moon is 720 N. D.) His mass on the moon is 12 kg E.) His mass on the moon is 72 kg F.) His weight on the moon is 120 N

His mass on the moon is 72 kg His weight on the moon is 120 N

What are the possible values of a vector component A.) Positive only B.) Positive or zero only C.) Positive or negative only D.) Positive, negative or zero

Positive, negative or zero

A car is stopped at a stop sign when a driver of a large truck not seeing the stop sign slams into the car from behind. Which one of the following statements is true? A.) The magnitude of the force exerted by the truck on the car is same as the magnitude of the force exerted by the car on the truck B.) The truck exerts a force on the car and the car does not exert a force on the truck C.) The force that the truck exerts on the car has a larger magnitude than the force that the car exerts on the truck D.) The force that the car exerts on the truck has a larger magnitude than the force that the truck exerts on the car

The magnitude of the force exerted by the truck on the car is same as the magnitude of the force exerted by the car on the truck

A textbook is resting on a table. Which one of the following statements is true? A.) Zero net force acts on the objects B.) Only one force acts on the objects C.) Constant nonzero net force acts on the object D.) No forces act on the object

Zero net force acts on the object B.)Two forces act on the textbook: gravity and the contact force from the table. C.) The textbook's velocity is constant D.)Two forces act on the textbook: gravity and the contact force from the table.

A box sits at rest on a table. The interaction pair to the weight of the box is the force from the _____ on the ______

box earth

The tension in an ideal cord in equilibrium is always the same at every location along the cord. True or false:

true

Select all of the following pairs of coordinate axes that are valid a.) x-axis east, y-axis north b.) x-axis east, y-axis northeast c.) X-axis horizontal, y-axis vertical d.) x-axis east, y-axis west e.) x-axis vertical, 7-axis horizontal

x-axis east, y-axis north X-axis horizontal, y-axis vertical x-axis vertical, 7-axis horizontal

A box is sliding down an inclined surface. What is the magnitude of the friction force on the box? A.)μsN B.) zero C.) μkN D.) μkmg

μkN A.) The object is not stationary on the surface, and kinetic friction is acting on the object B.) The object is sliding on a surface, and friction cannot be ignored C. D.)fk = μkN. However, since the surface is inclined, N ≠ mg.

Which of the following are scalars A.) 8 N up B.) Up C.) North D.) 3N E.) 1 N north F.) 5N

3N 5N

The x component of a vector is 3 N, and its y component is 4 N. What is its magnitude? A.) 4N B.) 5N C.) 3N D.) 1N E.) 7N

5N Notes: The square root of the sum of 3 N squared 4 N squared is 5N

Select all of the following that could be the magnitude of a vector A.) -7N B.) 0N C>) -4N D.) 8N E.) 5N

8N 5N 0N magnitudes are never negative

Select all the ways that a vector can be specified A.) By its magnitude and direction B.) By its direction C.) By only its magnitude D.) By any two components E.) By its components

By its magnitude and direction By its components Notes: Vector do have a direction, but they also have magnitude Scalars have only a magnitude, but vectors have both a magnitude and a direction Two components would tell us the direction in a plane, but third component is still needed to find the direction in space and the magnitude

In which situations do long-range forces apply? A.) Every Situation B.) Only when the objects are touching C.) Only when the objects aren't touching D.) No situation

Every Situation

Consider vector A→ in two dimensions. Its magnitude is A, and θ is the angle the vector makes with the positive x axis. Which of the following expressions is equal to θ?

Tan -1 (Ay/Ax)

The sum of two vectors is equal to the zero vector. Select all statements that are true. A.)The two vectors point in opposite direction B.) The two vectors have the same magnitude C.) The two vectors have different magnitudes D.) The two vectors point in the same direction E.) The two vectors are perpendicular

The two vectors point in opposite direction The two vectors have the same magnitude