Physics Multiple Choice (Ch. 2 - 4), Chapter 2 Physics practice, Physics I Frostburg Study Guide CH 1,2,3,4

An object is moving with constant non-zero acceleration in the +x direction. The velocity versus time graph of this object is

a straight line making an angle with the time axis.

You are in the middle of a large field. You walk in a straight line for 100 m, then turn left and walk 100 m more in a straight line before stopping. When you stop, you are 100 m from your starting point. By how many degrees did you turn left?

120

Four students use different instruments to measure the length of the same ball-point pen. Which measurement implies the greatest precision? Group of answer choices

160.0 mm

The sum of two vectors of fixed magnitudes has its minimum magnitude when the angle between these vectors is A) 180° B) 0° C) 360° D) 270° E) 90°

180

If a vector A has components Ax < 0, and Ay < 0, then the angle that this vector makes with the positive x-axis must be in the range

180° to 270°

The number 0.0078 has how many significant figures?

2

In which of the following cases does a car have a negative velocity and a positive acceleration? A car that is traveling in the

-x direction decreasing in speed

Roughly what might be the uncertainty in the times obtained by hand using a stopwatch? Group of answer choices

.3s

Galileo is to Aristotle as Copernicus is to Ptolemy. Group of answer choices

true

If A + B = 0, then the vectors A and B have equal magnitudes and are directed in the same direction.

true

The magnitude of a vector can never be less than the magnitude of any of its components

true

The magnitude of a vector is zero only if all of its components are zero

true

A ball is thrown straight up. What are the velocity and acceleration of the ball at the highest point in its path?

v = 0, a = 9.8 m/s2 down.

A ball is thrown downward at a speed of 20 m/s. Choosing the +y axis pointing up and neglecting air resistance, which equations could be used to solve for other variables? The downward acceleration due to gravity is g = 9.8 m/s2

y = y0 + (-20 m/s) t - (1/2)gt2

Vector T as expressed in terms of vectors M and N is given by

M+N

A bullet fired from a rifle begins to fall

as soon as it leaves the barrel

The 'cgs' in 'cgs system' stands for

centimeter-grams-seconds

A ball is thrown horizontally from the top of a tower at the same instant that a stone is dropped vertically. Which object is traveling faster when it hits the level ground below if neither of them experiences any air resistance?

the ball

The current definition of the standard meter of length is based on

the distance traveled by light in a vacuum

The current definition of the standard second of time is based on

the frequency of radiation emitted by cesium atoms.

The current definition of the standard kilogram of mass is based on

the mass a particular sample kept in France

James and John dive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. If there is no air resistance, when they reach the lake below

the splashdown speed of John is larger than that of James.

If a vector A has components Ax > 0, and Ay < 0, then the angle that this vector makes with the positive x-axis must be in the range

270° to 360°

How many significant figures should 1.362 + 25.2 have? Group of answer choices

3

You are adding vectors of length 20 and 40 units. Which of the following choices is a possible resultant magnitude?

37

The graph in the figure shows the position of a particle as it travels along the x-axis. At what value of t is the speed of the particle equal to 0 m/s?

3s

The percent uncertainty in the radius r = 0.84 ± 0.04 m of a beach ball is

5%

Using the French Academy of Sciences' original definition of the meter, the Earth's radius would be

6370 km

A student adds two displacement vectors that have the magnitudes of 12.0 m and 5.0 m. What is the range of possible answers for the magnitude of the resultant vector?

7 m < R < 17 m

If a vector A has components Ax < 0, and Ay > 0, then the angle that this vector makes with the positive x-axis must be in the range

90° to 180°

A ball is thrown downward at a speed of 20 m/s. Choosing the +y axis pointing up and neglecting air resistance, which equations could be used to solve for other variables? The downward acceleration due to gravity is g = 9.8 m/s2.

All of the above

You are trying to cross a river that flows toward the south with a strong current. You start out in your motorboat on the east bank desiring to reach the west bank directly west from your starting point. You should head your motorboat A) in a general southwesterly direction. B) in a general northwesterly direction. C) directly toward the west. D) directly toward the north.

B) in a general northwesterly direction.

You drop a rock off a bridge. When the rock has fallen 4 m, you drop a second rock. As the two rocks continue to fall, what happens to their velocities?

Both increase at the same rate.

Mary and Debra stand on a snow-covered roof. They both throw snowballs with the same initial speed, but in different directions. Mary throws her snowball downward, at 30° below the horizontal; Debra throws her snowball upward, at 30° above the horizontal. Which of the following statements are true about just as the snowballs reach the ground below?

Both snowballs will hit the ground with the same speed.

A child standing on a bridge throws a rock straight down. The rock leaves the child's hand at time t = 0 s. If we take upward as the positive direction, which of the graphs shown below best represents the velocity of the stone as a function of time?

C

Mary and Debra stand on a snow-covered roof. They both throw snowballs with the same initial speed, but in different directions. Mary throws her snowball downward, at 30° below the horizontal; Debra throws her snowball upward, at 30° above the horizontal. Which of the following statements are true about just before the snowballs reach the ground below?

Debra's snowball will stay in the air longer than Mary's snowball.

You drive 4 km at 30 km/h and then another 4 km at 50 km/h. What is your average speed for the whole 8-km trip?

Equal to 40 km/h.

The graph in the figure shows the position of an object as a function of time. The letters H-L represent particular moments of time. At which moment in time is the speed of the object equal to zero?

I

You are riding in an enclosed train car moving at 90 km/h. If you throw a baseball straight up, where will the baseball land?

In your hand

Suppose that a car traveling to the west (-x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct?

Its acceleration is positive.

A rock is thrown from the upper edge of a tall cliff at some angle above the horizontal. It reaches its highest point and starts falling down. Which of the following statements about the rock's motion are true just before it hits the ground?

Its horizontal velocity component is the same as it was just as it was launched.

The graph in the figure shows the position of an object as a function of time. The letters H-L represent particular moments of time. At which moment in time is the speed of the object the greatest?

J

James and John dive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. Compare the time it takes each to reach the lake below if there is no air resistance.

James and John will reach the surface of the lake in the same time.

You drive 4 km at 30 km/h and then another 4 km at 50 km/h. What is your average speed for the whole 8-km trip?

Less than 40 km/h.

Vector S as expressed in terms of vectors M and N is given by

M-N

A ball is dropped from the top of a tall building. At the same instant, a second ball is thrown upward from the ground level. When the two balls pass one another, one on the way up, the other on the way down, compare the magnitudes of their acceleration:

The acceleration of both balls is the same

One ball is dropped vertically from a window. At the same instant, a second ball is thrown horizontally from the same window. Which ball has the greater speed at ground level?

The dropped ball.

Which of the following statements are true about an object in two-dimensional projectile motion with no air resistance?

The horizontal acceleration is always zero and the vertical acceleration is always a non-zero constant downward.

The eastward component of vector A is equal to the westward component of vector B and their northward components are equal. Which one of the following statements must be correct for these two vectors?

The magnitude of vector A must be equal to the magnitude of vector B

At time t = 0 an object is traveling to the right along the +x axis at a speed of 10.0 m/s with acceleration -2.0 m/s2. Which statement is true?

The object will slow down, momentarily stopping, then pick up speed moving to the left.

Vector A is along the +x-axis and vector B is along the +y-axis. Which one of the following statements is correct with respect to these vectors?

The y component of vector A is equal to the x component of vector B.

In an air-free chamber, a pebble is thrown horizontally, and at the same instant a second pebble is dropped from the same height. Compare the times of fall of the two pebbles.

They hit at the same time

A boulder rolls off of a very high cliff and experiences no significant air resistance. While it is falling, its trajectory is never truly vertical

True

A theory is broader than a model.

True

Consider a car that travels between points A and B. The car's average speed can be greater than the magnitude of its average velocity, but the magnitude of its average velocity can never be greater than its average speed. (T or F)

True

Consider a deer that runs from point A to point B. The distance the deer runs can be greater than the magnitude of its displacement, but the magnitude of the displacement can never be greater than the distance it runs. (T orF)

True

Precision refers to the repeatability of a measurement

True

Vectors M and N obey the equation M + N = 0. These vectors satisfy which one of the following statements?

Vectors M and N have the same magnitudes

An object is moving with constant non-zero velocity in the +x direction. The velocity versus time graph of this object is

a horizontal straight line

An object is moving with constant non-zero acceleration in the +x direction. The velocity versus time graph of this object is

a horizontal straight line.

An object is moving with constant non-zero acceleration in the +x direction. The position versus time graph of this object is

a parabolic curve

A child standing on a bridge throws a rock straight down. The rock leaves the child's hand at time t = 0 s. If we take upward as the positive direction, which of the graphs shown below best represents the acceleration of the stone as a function of time?

b

A hunter is aiming horizontally at a monkey who is sitting in a tree. The monkey is so terrified when it sees the gun that it falls off the tree. At that very instant, the hunter pulls the trigger. What will happen?

b. The bullet will hit the monkey because both the monkey and the bullet are falling downward at the same rate due to gravity.

A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will

be in front of the package

A baseball is hit high and far. Which of the following statements is true? At the highest point, Group of answer choices

c. the magnitude of the velocity is the slowest.

Consider two vectors A and B shown in the figure. The difference B - A is best illustrated by

choice (b)

Consider two vectors A and B shown in the figure. The difference A - B is best illustrated by

choice (c)

Shown below are the velocity and acceleration vectors for an object in several different types of motion. In which case is the object slowing down and turning to its right?

choice B)

The motion of a particle is described in the velocity vs. time graph shown in the figure. Over the nine-second interval shown, we can say that the speed of the particle

decreases and then increases.

A baseball player hits a ball that soars high into the air. After the ball has left the bat, and while it is traveling upward, what is the direction of acceleration? Ignore air resistance

downward

17.2 mi = 27.68 km.

false

37) The Moon is accelerated toward the earth, so it is gradually getting closer to the earth. A) True B) False C) The moon is not accelerated toward the earth.

false

If three vectors add to zero, they must all have equal magnitudes

false

Scientists use the metric system chiefly because it is more accurate than the English system

false

The more digits an answer has, the more accurate it is.

false

The sine of 30.0° should be expressed as 0.5

false

The uncertainty in 952 is likely to ±10

false

When adding two numbers, the number of significant figures in the sum is equal to the number of significant figures in the least accurate of the numbers being added.

false

When determining the number of significant figures in a number, zeroes to the left of the decimal point are never counted.

false

If a tree is 15 m tall, its height is

greater than 15 ft

If an operatic aria lasts for 5.75 min, its length is

greater than 5.75 secs

If a flower is 6.5 cm wide, its width is

greater than 6.5 mm

Accuracy represents

how close a measurement is to the true value

You are trying to cross a river that flows toward the south with a strong current. You start out in your motorboat on the east bank desiring to reach the west bank directly west from your starting point. You should head your motorboat

in a general northwesterly direction

For general projectile motion with no air resistance, the horizontal component of a projectile's acceleration

is always zero

If a woman weighs 125 lb, her mass is

less than 125 kg

The magnitude of a component of a vector must be

less than or equal to the magnitude of the vector.

Which of the following is a SI base unit

m, s, km (all of the above)

If the velocity versus time graph of an object is a horizontal line, the object is

moving with zero acceleration

To convert from ft2 to yd2, you should

multiply by 1/9

A player kicks a soccer ball in a high arc toward the opponent's goal. At the highest point in its trajectory Group of answer choices

neither the ball's velocity nor its acceleration are zero.

If A + B = C and their respective magnitudes are given by A + B = C, then the vectors A and B are oriented

parallel to each other (in the same direction).

For general projectile motion with no air resistance, the vertical component of a projectile's acceleration

remains a non-zero constant

For general projectile motion with no air resistance, the horizontal component of a projectile's velocity

remains a non-zero constant.

A student's weight displayed on a digital scale is 117.2 lb. This would suggest her weight is

somewhere between 117.0 and 117.4 lbs

If A - B = 0, then the vectors A and B have equal magnitudes and are directed in the same direction. (t or f)

false

If a vector's components are all negative, then the magnitude of the vector is negative.

false

If three vectors add to zero, they must all have equal magnitudes.

false

If a vector pointing upward has a positive magnitude, a vector pointing downward has a negative magnitude. (t or f)

False

If the acceleration of an object is zero, then that object cannot be moving. (t or f)

False

If the velocity of an object is zero at some point, then its acceleration must also be zero at that point. (t or f)

False

If the velocity of an object is zero, then that object cannot be accelerating. (t or f)

False

Ball A is dropped from the top of a building. One second later, ball B is dropped from the same building. Neglect air resistance. As time progresses, the difference in their speeds A) increases. B) remains constant. C) decreases. D) cannot be determined from the information given.

B) remains constant.

The magnitude of the resultant of two vectors cannot be less than the magnitude of either of those two vectors. (t or f)

False

If a vector A has componentsAx< 0, andAy < 0, then the angle that this vector makes with the positivex-axis must be in the range A) 180° to 270° B) 0° to 90° C) 270° to 360° D) 90° to 180° E) cannot be determined without additional information

A) 180° to 270°

If a vector A has componentsAx< 0, andAy > 0, then the angle that this vector makes with the positivex-axis must be in the range A) 90° to 180° B) 0° to 90° C) 270° to 360° D) 180° to 270° E) It cannot be determined without additional information.

A) 90° to 180°

The sum of two vectors of fixed magnitudes has the greatest magnitude when the angle between these two vectors is A) 60° B) 270° C) 0° D) 90° E) 180°

0

Two vectors, of magnitudes 20 mm and 50 mm, are added together. Which one of the following is a possible value for the magnitude of the resultant? A) 40 mm B) 80 mm C) 20 mm D) 10 mm

40mm

A racing car accelerates uniformly from rest along a straight track. This track has markers spaced at equal distances along it from the start, as shown in the figure. The car reaches a speed of 140 km/h as it passes marker 2. Where on the track was the car when it was traveling at half this speed, that is at 70 km/h? A) Before marker 1 B) At marker 1 C) Between marker 1 and marker 2

A) Before marker 1

Suppose that a car traveling to the west (-x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct? A) Its acceleration is positive. B) Its acceleration is negative. C) Its acceleration is zero. D) Its acceleration is decreasing in magnitude as the car slows down.

A) Its acceleration is positive.

18) If the velocity of an object is zero at one instant, what is true about the acceleration of that object? (There could be more than one correct choice.) A) The acceleration could be positive. B) The acceleration could be negative. C) The acceleration could be zero. D) The acceleration must be zero.

A) The acceleration could be positive. B) The acceleration could be negative. C) The acceleration could be zero.

Suppose that a car traveling to the west begins to slow down as it approaches a traffic light. Which of the following statements about its acceleration is correct? A) The acceleration is toward the east. B) Since the car is slowing down, its acceleration must be negative. C) The acceleration is zero. D) The acceleration is toward the west.

A) The acceleration is toward the east.

Which of the following statements are true about an object in two-dimensional projectile motion with no air resistance? (There could be more than one correct choice.) A) The horizontal acceleration is always zero and the vertical acceleration is always a non-zero constant downward. B) The speed of the object is constant but its velocity is not constant. C) The speed of the object is zero at its highest point. D) The acceleration of the object is +g when the object is rising and -g when it is falling. E) The acceleration of the object is zero at its highest point.

A) The horizontal acceleration is always zero and the vertical acceleration is always a non-zero constant downward.

Which of the following graphs represent an object at rest? (There could be more than one correct choice.) A) graph a B) graph b C) graph c D) graph d E) graph e

A) graph a

29) Two objects are dropped from a bridge, an interval of 1.0 s apart. Air resistance is negligible. During the time that both objects continue to fall, their separation A) increases. B) decreases. C) stays constant. D) increases at first, but then stays constant. E) decreases at first, but then stays constant.

A) increases.

For general projectile motion with no air resistance, the horizontal component of a projectile's velocity A) remains a non-zero constant. B) continuously decreases. C) first decreases and then increases. D) continuously increases. E) remains zero.

A) remains a non-zero constant.

2) Which of the following quantities has units of a displacement? (There could be more than one correct choice.) A) 32 ft/s2 vertically downward B) 40 km southwest C) 9.8 m/s2 D) -120 m/s E) 186,000 mi

B) 40 KM southwest E) 186,000 miles

Mary and Debra stand on a snow-covered roof. They both throw snowballs with the same initial speed, but in different directions. Mary throws her snowball downward, at 30° below the horizontal; Debra throws her snowball upward, at 30° above the horizontal. Which of the following statements are true about just as the snowballs reach the ground below? (There could be more than one correct choice.) A) Debra's snowball will have a higher speed than Mary's snowball. B) Both snowballs will hit the ground with the same speed. C) Mary's snowball will have a higher speed than Debra's snowball. D) Mary's snowball reaches the ground before Debra's snowball. E) Both snowballs hit the ground at the same time.

B) Both snowballs will hit the ground with the same speed.

A ball is thrown downward in the absence of air resistance. After it has been released, which statement(s) concerning its acceleration is correct? (There could be more than one correct choice.) A) Its acceleration is constantly increasing. B) Its acceleration is constant. C) Its acceleration is constantly decreasing. D) Its acceleration is zero. E) Its acceleration is greater than g.

B) Its acceleration is constant.

Suppose that a car traveling to the east (+x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct? A) Its acceleration is in the +x direction. B) Its acceleration is in the -x direction. C) Its acceleration is zero. D) Its acceleration is decreasing in magnitude as the car slows down.

B) Its acceleration is in the -x direction.

A ball is thrown straight up, reaches a maximum height, then falls to its initial height. Which of the following statements about the direction of the velocity and acceleration of the ball as it is going up is correct? A) Both its velocity and its acceleration point upward. B) Its velocity points upward and its acceleration points downward. C) Its velocity points downward and its acceleration points upward. D) Both its velocity and its acceleration points downward.

B) Its velocity points upward and its acceleration points downward

Under what condition is average velocity equal to the average of the object's initial and final velocity? A) This can only occur if there is no acceleration. B) The acceleration is constant. C) This can occur only when the velocity is zero. D) The acceleration must be constantly increasing. E) The acceleration must be constantly decreasing.

B) The acceleration is constant.

The eastward component of vector A is equal to the westward component of vector B and their northward components are equal. Which one of the following statements must be correct for these two vectors? A) Vector A is parallel to vector B . B) The magnitude of vector A must be equal to the magnitude of vector B . C) Vector A is antiparallel (in the opposite direction) to vector B . D) The angle between vector A and vector B must be 90°. E) Vector A must be perpendicular to vector B .

B) The magnitude of vector A must be equal to the magnitude of vector B .

21) When a ball is thrown straight up with no air resistance, the acceleration at its highest point A) is upward B) is downward C) is zero D) reverses from upward to downward E) reverses from downward to upward

B) is downward

42) If the velocity versus time graph of an object is a straight line making an angle of +30° (counter clockwise) with the time axis, the object is A) moving with constant non-zero speed. B) moving with constant non-zero acceleration. C) at rest. D) moving with increasing acceleration.

B) moving with constant non-zero acceleration.

The slope of a position versus time graph gives A) the distance traveled. B) velocity. C) acceleration. D) displacement.

B) velocity.

James and John dive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. Compare the time it takes each to reach the lake below if there is no air resistance. A) John reaches the surface of the lake first. B) Cannot be determined without knowing the mass of both James and John. C) James and John will reach the surface of the lake at the same time. D) Cannot be determined without knowing the weight of both James and John. E) James reaches the surface of the lake first.

C) James and John will reach the surface of the lake at the same time.

27) A 10-kg rock and 20-kg rock are dropped from the same height and experience no significant air resistance. If it takes the 20-kg rock a time T to reach the ground, what time will it take the 10-kg rock to reach the ground? A) 4T B) 2T C) T D) T/2 E) T/4

C) T

Suppose that an object travels from one point in space to another. Make a comparison between the magnitude of the displacement and the distance traveled by this object. A) The displacement is either greater than or equal to the distance traveled. B) The displacement is always equal to the distance traveled. C) The displacement is either less than or equal to the distance traveled. D) The displacement can be either greater than, smaller than, or equal to the distance traveled.

C) The displacement is either less than or equal to the distance traveled.

Brick A is dropped from the top of a building. Brick B is thrown straight down from the same building, and neither one experiences appreciable air resistance. Which statement about their accelerations is correct? A) The acceleration of A is greater than the acceleration of B. B) The acceleration of B is greater than the acceleration of A. C) The two bricks have exactly the same acceleration. D) Neither brick has any acceleration once it is released.

C) The two bricks have exactly the same acceleration.

Two objects are thrown from the top of a tall building. One is thrown up, and the other is thrown down, both with the same initial speed. What are their speeds when they hit the street? Neglect air resistance. A) The one thrown up is traveling faster. B) The one thrown down is traveling faster. C) They are traveling at the same speed. D) It is impossible to tell because the height of the building is not given.

C) They are traveling at the same speed.

Vectors M and N obey the equation M + N = 0. These vectors satisfy which one of the following statements? A) Vectors M and N are at right angles to each other. B) The magnitude of M is the negative of the magnitude of N . C) Vectors M and N have the same magnitudes. D) Vectors M and N point in the same direction.

C) Vectors M and N have the same magnitudes.

A 10-kg rock and a 20-kg rock are dropped at the same time and experience no significant air resistance. If the 10-kg rock falls with acceleration a, what is the acceleration of the 20-kg rock? A) 4a B) 2a C) a D) a/2 E) a/4

C) a

An object is moving with constant non-zero velocity in the +x direction. The position versus time graph of this object is A) a horizontal straight line. B) a vertical straight line. C) a straight line making an angle with the time axis. D) a parabolic curve.

C) a straight line making an angle with the time axis.

If the position versus time graph of an object is a horizontal line, the object is A) moving with constant non-zero speed. B) moving with constant non-zero acceleration. C) at rest. D) moving with increasing speed.

C) at rest.

13) An auto manufacturer advertises that their car can go "from zero to sixty in eight seconds." This is a description of what characteristic of the car's motion? A) average speed B) instantaneous speed C) average acceleration D) instantaneous acceleration E) displacement

C) average acceleration

The area under a curve in a velocity versus time graph gives A) acceleration. B) velocity. C) displacement. D) position.

C) displacement.

23) Suppose a ball is thrown straight up and experiences no appreciable air resistance. What is its acceleration just before it reaches its highest point? A) zero B) slightly less than g C) exactly g D) slightly greater than g

C) exactly g

45) Which of the following graphs represent an object having zero acceleration? A) only graph a B) only graph b C) graphs a and b D) graphs b and c E) graphs c and d

C) graphs a and b

A 10-kg rock and a 20-kg rock are thrown upward with the same initial speed v0 and experience no significant air resistance. If the 10-kg rock reaches a maximum height h, what maximum height will the 20-kg ball reach? A) h/4 B) h/2 C) h D) 2h E) 4h

C) h

7) You drive 6.0 km at 50 km/h and then another 6.0 km at 90 km/h. Your average speed over the 12 km drive will be A) greater than 70 km/h. B) equal to 70 km/h. C) less than 70 km/h. D) exactly 38 km/h. E) It cannot be determined from the information given because we must also know directions traveled.

C) less than 70 km/h.

For general projectile motion with no air resistance, the vertical component of a projectile's acceleration A) first decreases and then increases. B) continuously decreases. C) remains a non-zero constant. D) continuously increases. E) is always zero.

C) remains a non-zero constant.

James and John dive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. If there is no air resistance, when they reach the lake below A) they will both have the same splashdown speed. B) the splashdown speed of James must be 9.8 m/s larger than that of John. C) the splashdown speed of John is larger than that of James. D) the splashdown speed of James is larger than that of John. E) the splashdown speed of John must be 25 m/s larger than that of James.

C) the splashdown speed of John is larger than that of James.

From the edge of a roof top you toss a green ball upwards with initial speed v0 and a blue ball downwards with the same initial speed. Air resistance is negligible. When they reach the ground below A) the green ball will be moving faster than the blue ball. B) the blue ball will be moving faster than the green ball. C) the two balls will have the same speed.

C) the two balls will have the same speed.

When is the average velocity of an object equal to the instantaneous velocity? A) only when the velocity is increasing at a constant rate B) only when the velocity is decreasing at a constant rate C) when the velocity is constant D) always E) never

C) when the velocity is constant

he graph in the figure shows the position of a particle as it travels along the x-axis. At what value of t is the speed of the particle equal to 0 m/s? A) 0 s B) 1 s C) 2 s D) 3 s E) 4 s

D) 3 s

The figure shows a graph of the position x of two cars, C and D, as a function of time t. According to this graph, which statements about these cars must be true? (There could be more than one correct choice.) A) The magnitude of the acceleration of car C is greater than the magnitude of the acceleration of car D. B) The magnitude of the acceleration of car C is less than the magnitude of the acceleration of car D. C) At time t = 10 s, both cars have the same velocity. D) Both cars have the same acceleration. E) The cars meet at time t = 10 s.

D) Both cars have the same acceleration. E) The cars meet at time t = 10 s.

22) A rock from a volcanic eruption is launched straight up into the air with no appreciable air resistance. Which one of the following statements about this rock while it is in the air is correct? A) On the way up, its acceleration is downward and its velocity is upward, and at the highest point both its velocity and acceleration are zero. B) On the way down, both its velocity and acceleration are downward, and at the highest point both its velocity and acceleration are zero. C) Throughout the motion, the acceleration is downward, and the velocity is always in the same direction as the acceleration. D) The acceleration is downward at all points in the motion. E) The acceleration is downward at all points in the motion except that is zero at the highest point.

D) The acceleration is downward at all points in the motion.

Suppose that an object is moving with a constant velocity. Which statement concerning its acceleration must be correct? A) The acceleration is constantly increasing. B) The acceleration is constantly decreasing. C) The acceleration is a constant non-zero value. D) The acceleration is equal to zero.

D) The acceleration is equal to zero.

43) The motions of a car and a truck along a straight road are represented by the velocity-time graphs in the figure. The two vehicles are initially alongside each other at time t = 0. At time T, what is true of the distances traveled by the vehicles since time t = 0? A) They will have traveled the same distance. B) The truck will not have moved. C) The car will have travelled further than the truck. D) The truck will have travelled further than the car.

D) The truck will have travelled further than the car.

An object moves in a circular path at a constant speed. Compare the direction of the object's velocity and acceleration vectors. A) Both vectors point in the same direction. B) The acceleration is zero but the velocity is constant. C) The vectors point in opposite directions. D) The vectors are perpendicular to each other.

D) The vectors are perpendicular to each other.

A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will A) be in front of the package. B) depend on the speed of the plane when the package was released. C) be behind the package. D) be directly over the package.

D) be directly over the package.

Two displacement vectors have magnitudes of 5.0 m and 7.0 m, respectively. If these two vectors are added together, the magnitude of the sum A) is equal to 2.0 m. B) is equal to 12 m. C) is equal to 8.6 m. D) could be as small as 2.0 m or as large as 12 m.

D) could be as small as 2.0 m or as large as 12 m.

The motion of a particle is described in the velocity vs. time graph shown in the figure. Over the nine-second interval shown, we can say that the speed of the particle A) only increases. B) only decreases. C) increases and then decreases. D) decreases and then increases. E) remains constant.

D) decreases and then increases.

You drive 4 km at 30 km/h and then another 4 km at 50 km/h. What is your average speed for the whole 8-km trip? a. More than 40 km/h. b. Equal to 40 km/h. c. Less than 40 km/h. d. Not enough information.

c. Less than 40 km/h

An object moving in the +x direction experiences an acceleration of +2.0 m/s2. This means the object A) travels 2.0 m in every second. B) is traveling at 2.0 m/s. C) is decreasing its velocity by 2.0 m/s every second. D) is increasing its velocity by 2.0 m/s every second.

D) is increasing its velocity by 2.0 m/s every second.

Which of the following situations is impossible? A) An object has velocity directed east and acceleration directed west. B) An object has velocity directed east and acceleration directed east. C) An object has zero velocity but non-zero acceleration. D) An object has constant non-zero acceleration and changing velocity. E) An object has constant non-zero velocity and changing acceleration.

E) An object has constant non-zero velocity and changing acceleration.

33) Mary and Debra stand on a snow-covered roof. They both throw snowballs with the same initial speed, but in different directions. Mary throws her snowball downward, at 30° below the horizontal; Debra throws her snowball upward, at 30° above the horizontal. Which of the following statements are true about just before the snowballs reach the ground below? (There could be more than one correct choice.) A) Mary's snowball will stay in the air longer than Debra's snowball. B) Mary's snowball has a greater downward acceleration than Debra's snowball. C) Both snowballs will take the same amount of time to hit the ground. D) Debra's snowball has exactly the same acceleration as Mary's snowball. E) Debra's snowball will stay in the air longer than Mary's snowball.

E) Debra's snowball will stay in the air longer than Mary's snowball.

A rock is thrown from the upper edge of a tall cliff at some angle above the horizontal. It reaches its highest point and starts falling down. Which of the following statements about the rock's motion are true just before it hits the ground? (There could be more than one correct choice.) A) Its vertical velocity component is the same as it was just as it was launched. B) Its velocity is vertical. C) Its horizontal velocity component is zero. D) Its speed is the same as it was just as it was launched. E) Its horizontal velocity component is the same as it was just as it was launched.

E) Its horizontal velocity component is the same as it was just as it was launched.

For general projectile motion with no air resistance, the horizontal component of a projectile's acceleration A) continuously increases. B) first decreases and then increases. C) remains a non-zero constant. D) continuously decreases. E) is always zero.

E) is always zero.

A player kicks a soccer ball in a high arc toward the opponent's goal. At the highest point in its trajectory A) the ball's velocity points downward. B) the ball's acceleration is zero but its velocity is not zero. C) both the velocity and the acceleration of the soccer ball are zero. D) the ball's acceleration points upward. E) neither the ball's velocity nor its acceleration are zero.

E) neither the ball's velocity nor its acceleration are zero.

A ball is thrown horizontally from the top of a tower at the same instant that a stone is dropped vertically. Which object is traveling faster when it hits the level ground below if neither of them experiences any air resistance? A) It is impossible to tell because we do not know their masses. B) the ball C) the stone D) Both are traveling at the same speed.

The ball

In an air-free chamber, a pebble is thrown horizontally, and at the same instant a second pebble is dropped from the same height. Compare the times of fall of the two pebbles. A) They hit at the same time. B) The dropped pebble hits first. C) The thrown pebble hits first. D) We cannot tell without knowing which pebble is heavier.

They hit at the same time

You drop a rock off a bridge. When the rock has fallen 4 m, you drop a second rock. As the two rocks continue to fall, what happens to their velocities? a. Both increase at the same rate. b. The velocity of the first rock increases faster than the velocity of the second. c. The velocity of the second rock increases faster than the velocity of the first. d. Both velocities stay constant.

a. Both increase at the same rate

A truck is traveling horizontally to the right. When the truck starts to slow down, the crate on the (frictionless) truck bed starts to slide. In what direction could the net force be on the crate? a. No direction. The net force is zero. b. Straight down (because of gravity). c. Straight up (the normal force). d. Horizontal and to the right. e. Horizontal and to the left.

a. No direction. The net force is zero.

You are trying to push your stalled car. Although you apply a horizontal force of 400 N to the car, it doesn't budge, and neither do you. Which force(s) must also have a magnitude of 400 N? a. The force exerted by the car on you. b. The friction force exerted by the car on the road. c. The normal force exerted by the road on you. d. The friction force exerted on the road on you.

a. The force exerted by the car on you. b. The friction force exerted by the car on the road. d. The friction force exerted on the road on you.

A bullet fired from a rifle begins to fall... a. as soon as it leaves the barrel. b. after air friction reduces its speed. c. not at all if air resistance is ignored.

a. as soon as it leaves the barrel.

A car travels 10 m/s east. Another car travels 10 m/s north. The relative speed of the first car with respect to the second is a. less than 20 m/s b. exactly 20 m/s c. more than 20 m/s

a. less than 20 m/s

To pull an old stump out of the ground, you and a friend tie two ropes to the stump. You pull on it with a force of 500 N to the north while your friend pulls with a force of 450 N to the northwest. The total force from the two ropes is: a. less than 950 N b. exactly 950 N c. more than 950 N

a. less than 950 N

The magnitude of a component of a vector must be: a. less than or equal to the magnitude of the vector b. equal to the magnitude of the vector c. greater than or equal to the magnitude of the vector. d. less than, equal to, or greater than the magnitude of the vector

a. less than or equal to the magnitude of the vector

You are in the middle of a large field. You walk in a straight line for 100 m, then turn left and walk 100 m more in a straight line before stopping. When you stop, you are 100 m from your starting point. By how many degrees did you turn? a. 90 b. 120 c. 30 d. 180 e. This is impossible. You cannot walk 200 m and be only 100 m away from where you started.

b. 120

A 50-N crate sits on a horizontal floor where the coefficient of static friction between the crate sand the floor is 0.50. A 20-N force is applied to the crate acting to the right. What is the resulting static friction force acting on the crate? a. 20 N to the right. b. 20 N to the left. c. 25 N to the right. d. 25 N to the left. e. None of the above; the crate starts to move.

b. 20 N to the left.

Which statements are NOT valid for a projectile? Take up as positive. a. The projectile has the same x velocity at any point on its path. b. The acceleration of the projectile is positive and decreasing when the projectile is moving upwards, zero at the top, and increasingly negative as the projectile descends. c. The acceleration of the projectile is a constant negative value. d. The y component of the velocity of the projectile is zero at the highest point of the projectile's path. e. The velocity at the highest point is zero.

b. The acceleration of the projectile is positive and decreasing when the projectile is moving upwards, zero at the top, and increasingly negative as the projectile descends. e. The velocity at the highest point is zero.

A hunter is aiming horizontally at a a monkey who is sitting in a tree. The monkey is so terrified when it sees the gun that it falls off the tree. At that very instant, the hunter pulls the trigger. What will happen? a. The bullet will miss the monkey because the monkey falls down while the bullet speeds straight forward. b. The bullet will hit the monkey because both the monkey and the bullet are falling downward at the same rate due to gravity. c. The bullet will miss the monkey because although both the monkey and bullet are falling downwards due to gravity, the monkey is falling faster. d. It depends on how far the hunter is from the monkey.

b. The bullet will hit the monkey because both the monkey and the bullet are falling downward at the same rate due to gravity.

A golf ball is hit with a golf club. While the ball flies through the air, which forces act on the ball? Neglect air resistance. a. The force of the golf club acting on the ball. b. The force of gravity acting on the ball. c. The force of the ball moving forward through the air. d. All of the above. e. Both (a) and (c).

b. The force of gravity acting on the ball.

One ball is dropped vertically from a window. At the same instant, a second ball is thrown horizontally from the same window. Which ball has the greater speed at ground level? a. The dropped ball. b. The thrown ball. c. Neither - they both have the same speed on impact. d. It depends on how hard the ball was thrown.

b. The thrown ball.

A ball is thrown downward at a speed of 20 m/s. Choosing the +y axis pointing up and neglecting air resistance, which equation(s) could be used to solve for other variables? The acceleration due to gravity is g = 9.8 m/s^2 downward. a. v = (20 m/s) - gt b. y = y_0 + (-20 m/s)t - (1/2)gt^2 c. v^2 = (20 m/s^2) - 2g(y - y_0) d. (20 m/s) = (v + v_0)/2 e. all of the above

b. y = y_0 + (-20 m/s)t - (1/2)gt^2 c. v^2 = (20 m/s^2) - 2g(y - y_0)

You are adding vectors of length 20 and 40 units. Which of the following choices is a possible resultant magnitude? a. 0 b. 18 c. 37 d. 64 e. 100

c. 37

You are riding in an enclosed train car moving at 90 km/h. If you throw a baseball straight up, where will the baseball land? a. In front of you. b. Behind you. c. In your hand. d. Can't decide from the given information.

c. In your hand.

A ball is dropped from the top of a tall building. At the same instant, a second ball is thrown upward from the ground level. When the two balls pass one another, one on the way up, the other on the way down, compare the magnitudes of their acceleration: a. The acceleration of the dropped ball is greater. b. The acceleration for the ball thrown upward is greater. c. The acceleration of both balls is the same. d. The acceleration changes during the motion, so you cannot predict the exact value when the two balls pass each other. e. The accelerations are in opposite directions.

c. The acceleration of both balls is the same

Suppose an object is accelerated by a force of 100 N. Suddenly a second force of 100 N in the opposite direction is exerted on the object, so that the forces cancel. The object... a. is brought to rest rapidly. b. decelerates gradually to rest. c. continues at the velocity it had before the second force was applied. d. is brought to rest and then accelerates in the direction of the second force.

c. continues at the velocity it had before the second force was applied.

A person stands on a scale in an elevator. His apparent weight will be the greatest when the elevator... a. standing still. b. is moving upward at a constant velocity. c. is accelerating upward. d. is moving downward at constant velocity. e. is accelerating downward.

c. is accelerating upward.

When a skier skis down a hill, the normal force exerted on the skier by the hill is... a. equal to the weight of the skier. b. greater than the weight of the skier. c. less than the weight of the skier.

c. less than the weight of the skier.

A baseball is hit high and far. Which of the following statements is true? At the highest point... a. the magnitude of the acceleration of the acceleration is zero. b. the magnitude of the velocity is zero. c. the magnitude of the velocity is the slowest. d. more than one of the above is true. e. none of the above are true.

c. the magnitude of the velocity is the slowest.

A ball is thrown straight up. What are the velocity and acceleration of the ball at the highest point in its path? a. v = 0, a = 0. b. v = 0, a = 9.8 m/s^2 up. c. v = 0, a = 9.8 m/s^2 down. d. v = 9.8 m/s up, a = 0.

c. v = 0, a = 9.8 m/s^2 down.

In which of the following cases does a car have a negative velocity and a positive acceleration? A car that is traveling in the... a. -x direction at a constant 20 m/s b. -x direction increasing in speed c. +x direction increasing in speed d. -x direction decreasing in speed e. +x direction decreasing in speed

d. -x direction decreasing in speed

At time t = 0 an object is traveling to the right along the +x axis at a speed of 10.0 m/s with acceleration -2.0 m/s^2. Which statement is true? a. The object will slow down, eventually coming to a complete stop. b. The object cannot have a negative acceleration and be moving to the right. c. The object will continue to move to the right, slowing down but never coming to a complete stop. d. The object will slow down, momentarily stopping, then pick up speed moving to the left.

d. The object will slow down, momentarily stopping, then pick up speed moving to the left.

A bear sling is used in some national parks for placing backpackers' food out of the reach of bears. As the backpacker raises the pack by pulling down on the rope, the force (F) needed: a. decreases as the pack rises until the rope is straight across. b. doesn't change. c. increases until the rope is straight. d. increases but the rope always sages where the pack hangs.

d. increases but the rope always sages where the pack hangs.

You are pushing a heavy box across a rough floor. When you are initially pushing the box and it is accelerating... a. you exert a force on the box, but the box does no exert a force on you. b. the box is so heavy it exerts a force on you, but you do not exert a force on the box. c. the force you exert on the box is greater than the forces of the box pushing back on you. d. the force you exert on the box is equal to the force of the box pushing back on you. e. the force that the box exerts on you is greater than the force you exert on the box.

d. the force you exert on the box is equal to the force of the box pushing back on you.

Matt is able to pull a large truck because... a. he is stronger than the truck. b. he is heavier in some respects than the truck. c. he exerts a greater force on the truck than the truck exerts back on him. d. the ground exerts a greater friction force on Matt than it does on the truck. e. the truck offers no resistance because its brakes are off.

d. the ground exerts a greater friction force on Matt than it does on the truck.

The normal force on an extreme skier descending a very steep slope can be zero if... a. his speed is not great enough. b. he leaves the slope (no longer touches the snow). c. the slope is greater than 75 degrees. d. the slope is vertical (90 degrees).

d. the slope is vertical (90 degrees).

The magnitude of a vector an only zero ifall of its components are zero.

true