physics exam 1

A honeybee leaves the hive and travels a total distance of 2 km before returning to the hive. What is the magnitude of the displacement vector of the bee?

0

If velocity is constant, then acceleration is what?

0

what us displacement if end up where started

0

velocity equation

Average Velocity= Xf-Xi/Tf-Ti

vector components

Ax and Ay

Fg (force of gravity)

Mg=w

What unit is defined by a 1-m/s2 acceleration of a 1-kg object?

Newton

A race finishes at the same place as it started. The contestants start from rest and cross the finish line running. Which one of the following is true about the average speed, the average velocity, and the average acceleration? Note that the symbol ≠ means "not equal to".

average speed ≠ 0 m/s, average velocity = 0 m/s, average acceleration ≠ 0 m/s2

Ay

asin(theta)

Which one of the following quantities is defined as the distance traveled divided by the elapsed time for the travel?

average speed

magnitude is always

positive

Acceleration

rate of change of velocity

Is the average speed of a vehicle a vector or a scalar quantity?

scalar

Which one of the following statements is true concerning scalar quantities? Scalar quantities must be represented by base units. Scalar quantities can be added to vector quantities using rules of trigonometry. Scalar quantities have both magnitude and direction. Scalar quantities can be added to other scalar quantities using rules of trigonometry. Scalar quantities can be added to other scalar quantities using rules of ordinary addition.

scalar quantities can be added to other scalar quantities using rules of ordinary addition.

a=positive

speeding up or moving to right

Q1

+/+

A book is resting on the surface of a table. Consider the following four forces that arise in this situation:(1) the force of the earth pulling on the book (3) the force of the book pushing on the table(2) the force of the table pushing on the book (4) the force of the book pulling on the earth Which two forces form an "action-reaction" pair that obeys Newton's third law?

1 and 4

force steps

1. identify object 2. identify forces acting on system 3. free body diagram 4. math

The velocity of a train is 80.0 km/h, due west. One and a half hours later its velocity is 65.0 km/h, due west. What is the train's average acceleration?

10.0 km/h2, due east

A straight track is 1600 m in length. A runner begins at the starting line, runs due east for the full length of the track, turns around and runs halfway back. The time for this run is five minutes.What is the magnitude of the runner's average velocity?

160

A sports car starts from rest. After 10.0 s, the speed of the car is 25.0 m/s. What is the magnitude of the car's acceleration?

2.50 m/s2

A horse pulls a cart along a flat road. Consider the following four forces that arise in this situation.(1) the force of the horse pulling on the cart (3) the force of the horse pushing on the road(2) the force of the cart pulling on the horse (4) the force of the road pushing on the horse Which two forces form an "action-reaction" pair that obeys Newton's third law?

3 and 4

A net force F→F→ is required to give an object with mass m an acceleration a→a→. If a net force 6F→6F→ is applied to an object with mass 2m, what is the acceleration on this object?

3a→

A boat moves 3.0 km due north and then moves 1.0 km due south. The time for this trip is half an hour. What is the average velocity of the boat?

4.0 km/h, due north

What constant acceleration would a car, starting from rest, have to sustain in order to reach a velocity of 27 m/s due east in 3.0 s?

9.0 m/s2, due east

The tail of a vector is fixed to the origin of an x, y axis system. Originally the vector points along the +x axis and has a magnitude of 12 units. As time passes, the vector rotates counterclockwise. For which of the following rotational angles is the x component of the vector equal to zero? 90 degrees 180 degrees 270 degrees 360 degrees

90 & 270

A ball is sitting in a child's wagon and a child is holding the wagon's handle. The ball then rolls to the back of the wagon without anyone touching the ball directly. Which of the following statements according to Newton's first law of motion could describe the motion of the wagon?Statement A: The wagon is moving forward, and the child suddenly increases the speed of the wagon.Statement B: The wagon is moving backward, and the child suddenly slows it down.Statement C: The wagon is at rest.

A and B only

In which one of the following situations does the car have an acceleration that is directed due north?

A car is traveling southward as its speed decreases from 24 m/s to 18 m/s.

Which one of the following statements is true according to Newton's third law of motion? A force on an object produces another differing in magnitude, but oppositely directed force on another object. A force on an object produces another differing in magnitude, but oppositely directed force on that object. A force on an object produces another equal in magnitude, but oppositely directed force on that object. The vector sum of all forces acting on an object is zero. A force on an object produces an equal in magnitude, but oppositely directed force on another object.

A force on an object produces an equal in magnitude, but oppositely directed force on another object.

friction

A force that opposes motion between two surfaces that are in contact

Which one of the following statements is true according to Newton's first law of motion? A net force is required to maintain an object's constant velocity. A net force is required to maintain an object at rest. A net force is required to change an object's velocity.

A net force is required to change an object's velocity.

In Case A an object is moving straight downward with a constant speed of 9.80 m/s, while in Case B an object is moving straight downward with a constant acceleration of magnitude 9.80 m/s2. Which one of the following is true? A nonzero net external force acts on the object in both cases. A nonzero net external force acts on the object in neither case. A nonzero net external force acts on the object in Case A only. A nonzero net external force acts on the object in Case B only.

A nonzero net external force acts on the object in Case B only. he statement is true because in Case A the object is moving with constant velocity, so the net force is zero. In Case B the object is accelerating so there is a nonzero net force.

scalar

A physical quantity that has magnitude only.

force

A push or a pull

vector

A quantity that has magnitude and direction

Ax

Acostheta

What is the difference between distance and displacement?

Displacement is a vector, while distance is not a vector.

Displacement

Distance and direction of an object's change in position from the starting point. (vector) meters

Which one of the following equations is associated with Newton's second law?

F=m⋅aF=m⋅a

Friction formula

Ff = uFn

Newton's Third Law of Motion

For every action there is an equal and opposite reaction

Newton's Second Law

Force equals mass times acceleration

contact forces

Fpush/pull, Fnormal, Ffriction, gravity, tension

static friction

Friction that acts on objects that are not moving

In physics, what is a push or pull on an object called?

force

Three runners start at the same place. Shaun runs 4.0 km due east and then runs 1.0 km due west. Mark runs 3.0 km due east. Jeff runs 2.0 km due west and then runs 5.0 km due east. Which of the following is true concerning the displacement of each runner?

Shaun, Mark, and Jeff have the same displacements.

Which one of the following statements concerning speed is true?

Speed is always a positive number

When a net force F is applied to an object of mass m, it's acceleration has a magnitude a. If the net force on the object is tripled, which one of the following statements is true? The mass of the object will be one third of its original value or m/3. Both the mass and the acceleration of the object will increase. The acceleration of the object will be three times its original value or 3a. The acceleration of the object will be one third of its original value or a/3. The mass of the object will be three times its original value or 3m.

The acceleration of the object will be three times its original value or 3a.

The vector A in the diagram has components labeled Ax and Ay. How would the direction of the vector A change if the magnitudes of Ax and Ay were doubled? (See the angle θ in the drawing.)

The angle θ would remain the same. Correct. The angle θ is determined by the inverse tangent function, θ=tan−1(AyAx)θ=tan⁡−1(AyAx). If Ax and Ay both become twice as large, the ratio does not change, and θ remains the same.

The drawings show three blocks sliding along horizontal surfaces. Each block has a different mass, as indicated. The coefficient of kinetic friction in each case is the same. Which block has the greatest deceleration?

The deceleration is the same in each case. Acceleration is inversely proportional to mass, according to Newton's second law. This law also indicates that acceleration is directly proportional to the net force. The frictional force is the net force acting on a block, and its magnitude is directly proportional to the magnitude of the normal force. However, in each of the pictures the normal force is directly proportional to the weight and, thus, to the mass of a block. The inverse proportionality of the acceleration to mass and the direct proportionality of the net force to mass offset each other. The result is that the deceleration is the same in each case.

The net external force acting on a dust particle in space is zero newtons. Which one of the following statements concerning this particle is true. The dust particle must be stationary. The dust particle is stationary or must be traveling at a constant velocity. The motion of the dust particle cannot be determined from the information given. The velocity of the dust particle must be changing. The dust particle must be moving at a constant velocity.

The dust particle is stationary or must be traveling at a constant velocity.

A vector is represented by an arrow. What is the significance of the length of the arrow?

The length of the arrow is proportional to the magnitude of the vector.

The net external force acting on an object is zero. Which one of the following statements is true? The object can only be stationary. The object can only be traveling with a constant velocity. The object can be either stationary or traveling with a constant velocity. The object can only be traveling with a velocity that is changing.

The object can be either stationary or traveling with a constant velocity.

Starting from rest, a particle confined to move along a straight line is accelerated at a rate of 2 m/s2. Which one of the following statements accurately describes the motion of this particle? The final speed of the particle will be proportional to the distance that the particle covers. The particle travels 2 m during each second. The speed of the particle increases by 2 m/s during each second. The acceleration of the particle increases by 2 m/s2 during each second. The particle travels 2 m only during the first second.

The speed of the particle increases by 2 m/s during each second.

Which one of the following situations involves a vector quantity? The light took approximately 500 s to travel from the sun to the earth. The mass of the Martian soil probe was 250 kg. The overnight low temperature in Toronto was -4.0°C. The volume of the soft drink can is 0.360 liters. The velocity of the rocket was 325 m/s, due east.

The velocity of the rocket was 325 m/s, due east.

equation to use if position not mentioned

Vf^2= Vix^2 + 2a(Xf-Xi)

displacement formula

Xf-Xi needs direction

what equation to use if small acceleration

Xf= Xi + Vi * T + 1/2at^2

what equation to use if a=0 (constant speed)

Xf=Xi + V * T

If forces are unbalanced, is there acceleration?

Yes, a force is acting on the object so it's motion will change and accelerate (+ acceleration = speeding up, - acceleration = slowing down) (2nd law)

Complete the following statement: Displacement is

a vector indicating the distance and direction from one point to another.

A net force F is required to give an object with mass m an acceleration a. If a net force 2F is applied to an object with mass 4m, what is the acceleration of this object?

a/2

Newton's first law of motion

an object in motion will remain in motion unless acted upon by another force v=0

Which of the following statements, if any, involves a vector? (Several choices may be correct.) (a) I walked 2 miles along the beach. (b) I walked 2 miles due north along the beach. (c) I jumped off a cliff and hit the water traveling at 17 miles per hour. (d) I jumped off a cliff and hit the water traveling straight down at a speed of 17 miles per hour. (e) My bank account shows a negative balance of -25 dollars.

b and d

Which of the following statements can be explained by Newton's first law? (A) When your car suddenly comes to a halt, you lunge forward. (B) When your car rapidly accelerates, you are pressed backward against the seat

both A and B Statement A illustrates Newton's first law because your body is initially moving forward, and when the car stops it continues forward. Statement B illustrates Newton's first law because your body tends to remain in its initial state (either rest or moving forward at some speed), so when the car accelerates forward, your body remains behind, pressing you backward in your seat.

The average acceleration is zero when __________

both the magnitudes and the directions of the initial and final velocities are the same. If neither the magnitude nor the direction of the velocity changes, then the velocity is constant, and the change in velocity is zero. Since the average acceleration is the change in velocity divided by the elapsed time, the average acceleration is also zero.

Vector points along the +y axis and has a magnitude of 100.0 units. Vector points at an angle of 60.0° above the +x axis and has a magnitude of 200.0 units. Vector points along the +x axis and has a magnitude of 150.0 units.Which vector has the largest x component? (One or more answers may be correct.)

c

2 types of forces

contact and long range

Complete the following statement: The net force that results when two or more forces act on an object is

determined using vector addition of the individual forces acting on the object.

Two buses depart from Chicago, one going to New York and one to San Francisco. Each bus travels at a speed of 30 m/s, so they have equal velocities. True

false

When using the equations of kinematics to solve motion problems, the velocity and acceleration variables will always be positive.

false When using the equations of kinematics to solve motion problems, the velocity and acceleration variables will always be positive.

A box containing supplies is vertically lowered at constant speed by a rope from a hovering helicopter. Consider the following forces that arise in this situation: force 1: the force of the earth pulling on the box force 2: the tension force acting on the box force 3: the force of the earth pulling on the helicopter force 4: the force of the box pulling on the EarthWhich two forces form an "action-reaction" pair that obeys Newton's third law?

forces 1 and 4

Which one of the following tools is useful in representing the forces acting on an object and simplifies problem solving? vector analyzer force monitor free-body diagram Newton's ladder scalar drawing

free body diagram

long range force

gravity

A cell phone is sitting on a desk. Which one of the following is the reaction force to the cell phone's weight on the desk? the normal force of the table on the cell phone the gravitational force by the cell phone on the Earth the gravitational force on the table the normal force of the Earth on the table the normal force of the cell phone on the table

he gravitational force by the cell phone on the Earth

Complete the following statement: A displacement vector

is directed from an object's initial position toward its final position.

a=negative

moving to left or slowing down

Ist Law of Motion

net F=0

In Case A an object is moving straight downward with a constant speed of 9.80 m/s, while in Case B an object is moving straight downward with a constant acceleration of magnitude 9.80 m/s2. Which one of the following is true? A nonzero net external force acts on the object in both cases. A nonzero net external force acts on the object in neither case. A nonzero net external force acts on the object in Case A only. A nonzero net external force acts on the object in Case B only

nonzero net external force acts on the object in Case B only. The statement is true because in Case A the object is moving with constant velocity, so the net force is zero. In Case B the object is accelerating so there is a nonzero net force.

An object in space is moving at a constant velocity. All of the following statements could be true concerning this situation, except one.Which one of the following statements concerning this situation is necessarily false? Two forces are acting simultaneously on the object. Only one force acts on the object. No forces are acting on the object. Three forces are acting simultaneously on the object.

only one force acts on the object.

kinetic friction force

the force that opposes relative motion between surfaces in contact

Q4

x=+ y=- 360-

Complete the following statement: The term net force most accurately describes

the quantity that changes the velocity of an object.

velocity

the speed and direction of an object in a particular direction (m/s)

Which one of the following quantities is a vector quantity? the mass of a watermelon the age of the pyramids in Egypt the number of people on board an airplane the sun's pull on the earth the temperature of molten lava

the sun's pull on the earth

On which one of the following does the average speed depend?

the total distance traveled

Q2

x=- y=+ 180-

Q3

x=- y=- 180+

distance

total length traveled (scalar, positive)

Since a force requires both a magnitude and a direction to completely describe it, forces are which kind of quantity - a scalar or a vector?

vectors

Complete the following statement: The difference between speed and velocity is

velocity has a direction, but speed does not.

Which one of the following quantities is defined as an object's displacement divided by the elapsed time for the displacement?

verage velocity

acceleration formula

vf-vi/tf-ti

In which one of the following situations can the equations of kinematics not be used? hen the velocity changes from moment to moment when the acceleration remains constant when the velocity remains constant when the acceleration changes from moment to moment

when the acceleration changes from moment to moment