Question 1

Suppose a jet is cruising at a constant velocity due east. At the instant the jet is above your head, what is the direction of the jet's angular momentum around you? Choose from the possible directions presented in problem C7T.3, remembering that this is a top view, with A corresponding to north, C to east, and so on.

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  Upward
F) Downward
G) (The vector is zero)

Question 2

If two moving objects collide, we can always orient our reference frame so that the collision takes place entirely in the $x y$ plane.

Accepted Answer

A) True 
 B)False

Question 3

In the hypothetical atomic interaction shown in figure C9.13, assume that initially the atoms have zero velocity at a separation of $r=0.2 \mathrm{~nm}$. How will their separation subsequently evolve with time?

Accepted Answer

A)  It will remain fixed at $r=0.2 \mathrm{~nm}$. 
B)  It will oscillate between $r=0.2 \mathrm{~nm}$ and $\boldsymbol{r}=\mathbf{0 . 0 6 \mathrm { nm }}$. 
C)  It will decrease to about $r=0.06 \mathrm{~nm}$, rebound, and then increase to essentially infinite separation. 
D)  It will increase to essentially infinite separation. 
E)  Some other behavior (specify).

Question 4

In a situation where an object can move only along the $x$ axis, a book states "the force on the object is $\mathrm{F}=$ $k x$, where $k$ is a constant, and $x$ is the object's position coordinate." Is $F$ being used here as a shorthand symbol for $|\vec{F}|(A)$ or $F_{x}(C)$ ?
$\bullet$ A
$\bullet$ C

Accepted Answer

The answer of In a situation where an object can...

Question 5

Consider the types of reference frames listed below.
(NRF = nonrotating frame)

-A NRF attached to a satellite orbiting the earth
A. A NRF in deep space
B. A NRF that is freely floating
C. A NRF attached to the earth's center of mass
D. A frame attached to the earth's surface (or a similarly slowly rotating object)
E. A frame moving at a constant velocity relative to one of the frame types described above
F. A noninertial frame

Accepted Answer

The answer of Consider the types of reference frames listed...

Question 6

Which of the following things is an "extended object"? For each item, answer "A" if the item is an acceptable extended object, " $\mathrm{B}$ " if the definition of an extended object applies badly to the item, and " $\mathrm{D}$ " if it is debatable.
-The earth's atmosphere

Accepted Answer

The answer of Which of the following things is an...

Question 7

Suppose a moving cart (cart $A$ ) hits an identical cart (cart $B$ ) at rest. Cart $B$ remains at rest after the collision, and cart $A$ rebounds with a speed equal to its original speed. Cart $B$ must have participated in some other interaction during the collision process,

Accepted Answer

A) True 
 B)False

Question 8

Consider a point $P$ midway between two particles, one with charge $-q$ and one with charge $q$. The potential $\phi$ at point $P$ is zero.

Accepted Answer

A) True 
 B)False

Question 9

The heat energy released by a 1-kg bottle of water as its temperature decreases by $1^{\circ} \mathrm{C}$ could (if we could convert it to gravitational potential energy) lift that bottle hundreds of meters into the air.

Accepted Answer

A) True 
 B)False

Question 10

The thermal energy of a block of ice at $0^{\circ} \mathrm{C}$ melting to a puddle of water at $0^{\circ} \mathrm{C}$ in a cup at room temperature

Accepted Answer

A)  Increases. 
B)  Decreases. 
C)  Remains the same.

Question 11

In the situation discussed in problem C4T.10, which would be the easiest reasonably valid frame to use?

Accepted Answer

A) True 
 B)False

Question 12

A railroad car collides with a similar car at rest. The cars lock together. Such a process must convert a significant fraction of the originally moving car's kinetic energy to thermal energy

Accepted Answer

A) True 
 B)False

Question 13

The speed $V$ of sound waves in a gas like air might plausibly depend on the gas's pressure $P$ (which has units of $\mathrm{N} / \mathrm{m}^{2}$ ), the gas's density $\rho$ (which has units of $\mathrm{kg} / \mathrm{m}^{3}$ ) and its temperature $T$ (which has units of $\mathrm{K}$ ), and some unitless constant $C$. Assuming that no other quantities are relevant, which of the following formulas might possibly correctly give the speed of sound in a gas?

Accepted Answer

A)  $v=\mathrm{CP} \rho \mathrm{T}$ 
B)  $v=\mathrm{CTP} / \rho$ 
C)  $V=\mathrm{CP} / \rho$ 
D)  $v=C \sqrt{P / \rho}$ 
E)  $V=C \sqrt{\rho / P}$
F)$ v=\mathrm{C}(\mathrm{P} / \rho)^{2}$
G) None of these can be correct.

Question 14

Suppose sand is leaking from an unpowered but moving railroad car. Since the sand is moving forward along with the car as it leaks out, it carries kinetic energy out of the car. This mass transfer will

Accepted Answer

A)  Cause the car's speed to increase. 
B)  Cause the car's speed to decrease. 
C)  Have no effect on the car's speed.

Question 15

Suppose I throw a ball toward the floor. It hits the floor and rebounds upward. What type of interaction causes the ball to rebound?

Accepted Answer

A)  Gravitational 
B)  Electrostatic 
C)  Magnetic 
D)  Compression 
E)  Friction
F) Tension
G) Something else (explain)

Question 16

Which of the following expressions gives the correct units for the volt in terms of base SI units?

Accepted Answer

A)  $1 \mathrm{~V}=1 \mathrm{~kg} \cdot \mathrm{m}^{2} \mathrm{C}^{-1} \mathrm{~s}$ 
B)  $1 \mathrm{~V}=1 \mathrm{~kg} \cdot \mathrm{m}^{2} \mathrm{~A}^{-1} \mathrm{~s}^{-3}$ 
C)  $1 \mathrm{~V}=1 \mathrm{~kg} \cdot \mathrm{m} \cdot \mathrm{A}^{-1} \mathrm{~s}^{-1}$ 
D)  $1 \mathrm{~V}=1 \mathrm{~kg} \cdot \mathrm{m}^{2} \mathrm{~s}^{-2} \mathrm{C}^{-2}$ 
E)  $1 \mathrm{~V}=1 \mathrm{~J} / \mathrm{C}$
F) Some other expression (specify).

Question 17

In the situation described in problem C10T.5, will the car's internal energy increase, decrease, or remain unchanged? (Be prepared to explain your answer in terms of the momentum requirement and the work done.)

Accepted Answer

A)  Increase 
B)  Decrease 
C)  Remain unchanged 
D)  One needs more information to answer

Question 18

A hydrogen atom consists of an electron (with negative charge) orbiting a proton (with positive charge). With the conventional definition of the reference position for electrostatic potential energy, the electrostatic potential energy for this system

Accepted Answer

A)  is positive. 
B)  is zero. 
C)  is negative. 
D)  depends on how fast the electron is moving.

Question 19

Suppose a $1.0-\mathrm{kg}$ object traveling rightward at $1.0 \mathrm{~m} / \mathrm{s}$ hits a $3.0 \mathrm{~kg}$ object at rest. Afterward, we observe the lighter object to move leftward with a speed of $0.75 \mathrm{~m} / \mathrm{s}$. What impulse did the collision interaction give the smaller object at the expense of the larger?

Accepted Answer

A)  None; the larger object was at rest and so had no momentum to give the smaller object. 
B)  None; the smaller object gave an impulse to larger, not the other way around. 
C)  $0.75 \mathrm{~kg} \cdot \mathrm{m} / \mathrm{s}$ leftward. 
D)  $1.0 \mathrm{~kg} \cdot \mathrm{m} / \mathrm{s}$ leftward. 
E)  $1.75 \mathrm{~kg} \cdot \mathrm{m} / \mathrm{s}$ leftward.

Question 20

The following diagrams show hypothetical results for collisions between identical balls floating in space. One ball was originally moving to the right along the dashed line before striking the other ball at rest. (The collision was not necessarily head-on.) The arrows depict the balls' final velocities. Which outcomes are physically believable? 
-
A) if it is absurd.
B)if the outcome is believable

Accepted Answer

The answer of The following diagrams show hypothetical results for...

Exam 1: Conservation Laws Constrain Interactions

If two moving objects collide, we can always orient our reference frame so that the collision takes place entirely in the $x y$ plane.

Which of the following things is an "extended object"? For each item, answer "A" if the item is an acceptable extended object, " $\mathrm{B}$ " if the definition of an extended object applies badly to the item, and " $\mathrm{D}$ " if it is debatable. -The earth's atmosphere

Suppose a moving cart (cart $A$ ) hits an identical cart (cart $B$ ) at rest. Cart $B$ remains at rest after the collision, and cart $A$ rebounds with a speed equal to its original speed. Cart $B$ must have participated in some other interaction during the collision process,

Consider a point $P$ midway between two particles, one with charge $-q$ and one with charge $q$ . The potential $\phi$ at point $P$ is zero.

The heat energy released by a 1-kg bottle of water as its temperature decreases by $1^{\circ} \mathrm{C}$ could (if we could convert it to gravitational potential energy) lift that bottle hundreds of meters into the air.

The thermal energy of a block of ice at $0^{\circ} \mathrm{C}$ melting to a puddle of water at $0^{\circ} \mathrm{C}$ in a cup at room temperature

In the situation discussed in problem C4T.10, which would be the easiest reasonably valid frame to use?

A railroad car collides with a similar car at rest. The cars lock together. Such a process must convert a significant fraction of the originally moving car's kinetic energy to thermal energy

Suppose sand is leaking from an unpowered but moving railroad car. Since the sand is moving forward along with the car as it leaks out, it carries kinetic energy out of the car. This mass transfer will

Suppose I throw a ball toward the floor. It hits the floor and rebounds upward. What type of interaction causes the ball to rebound?

Which of the following expressions gives the correct units for the volt in terms of base SI units?

In the situation described in problem C10T.5, will the car's internal energy increase, decrease, or remain unchanged? (Be prepared to explain your answer in terms of the momentum requirement and the work done.)

A hydrogen atom consists of an electron (with negative charge) orbiting a proton (with positive charge) . With the conventional definition of the reference position for electrostatic potential energy, the electrostatic potential energy for this system

Exam 1: Conservation Laws Constrain Interactions

If two moving objects collide, we can always orient our reference frame so that the collision takes place entirely in the xyx yxy plane.

In the hypothetical atomic interaction shown in figure C9.13, assume that initially the atoms have zero velocity at a separation of r=0.2 nmr=0.2 \mathrm{~nm}r=0.2 nm . How will their separation subsequently evolve with time?

Which of the following things is an "extended object"? For each item, answer "A" if the item is an acceptable extended object, " B\mathrm{B}B " if the definition of an extended object applies badly to the item, and " D\mathrm{D}D " if it is debatable. -The earth's atmosphere

Suppose a moving cart (cart AAA ) hits an identical cart (cart BBB ) at rest. Cart BBB remains at rest after the collision, and cart AAA rebounds with a speed equal to its original speed. Cart BBB must have participated in some other interaction during the collision process,

Consider a point PPP midway between two particles, one with charge −q-q−q and one with charge qqq . The potential ϕ\phiϕ at point PPP is zero.

The heat energy released by a 1-kg bottle of water as its temperature decreases by 1∘C1^{\circ} \mathrm{C}1∘C could (if we could convert it to gravitational potential energy) lift that bottle hundreds of meters into the air.

The thermal energy of a block of ice at 0∘C0^{\circ} \mathrm{C}0∘C melting to a puddle of water at 0∘C0^{\circ} \mathrm{C}0∘C in a cup at room temperature

In the situation discussed in problem C4T.10, which would be the easiest reasonably valid frame to use?

A railroad car collides with a similar car at rest. The cars lock together. Such a process must convert a significant fraction of the originally moving car's kinetic energy to thermal energy

Suppose sand is leaking from an unpowered but moving railroad car. Since the sand is moving forward along with the car as it leaks out, it carries kinetic energy out of the car. This mass transfer will

Suppose I throw a ball toward the floor. It hits the floor and rebounds upward. What type of interaction causes the ball to rebound?

Which of the following expressions gives the correct units for the volt in terms of base SI units?

In the situation described in problem C10T.5, will the car's internal energy increase, decrease, or remain unchanged? (Be prepared to explain your answer in terms of the momentum requirement and the work done.)

A hydrogen atom consists of an electron (with negative charge) orbiting a proton (with positive charge) . With the conventional definition of the reference position for electrostatic potential energy, the electrostatic potential energy for this system

If two moving objects collide, we can always orient our reference frame so that the collision takes place entirely in the $x y$ plane.

Which of the following things is an "extended object"? For each item, answer "A" if the item is an acceptable extended object, " $\mathrm{B}$ " if the definition of an extended object applies badly to the item, and " $\mathrm{D}$ " if it is debatable. -The earth's atmosphere

Suppose a moving cart (cart $A$ ) hits an identical cart (cart $B$ ) at rest. Cart $B$ remains at rest after the collision, and cart $A$ rebounds with a speed equal to its original speed. Cart $B$ must have participated in some other interaction during the collision process,

Consider a point $P$ midway between two particles, one with charge $-q$ and one with charge $q$ . The potential $\phi$ at point $P$ is zero.

The heat energy released by a 1-kg bottle of water as its temperature decreases by $1^{\circ} \mathrm{C}$ could (if we could convert it to gravitational potential energy) lift that bottle hundreds of meters into the air.

The thermal energy of a block of ice at $0^{\circ} \mathrm{C}$ melting to a puddle of water at $0^{\circ} \mathrm{C}$ in a cup at room temperature