##### Document Text Contents

Page 1

Chapter 1, Introduction

CHAPTER 1

Conceptual Problems

C1. A room in a house has a floor area of 120 ft2. Which of the following is most likely the

approximate volume of the room?

a. 3 m3

b. 30 m3

c. 300 m3

d. 3 000 m3

C2. When SI units are plugged into an equation, it is found that the units balance. Which of the

following can we expect to be true for this equation?

a. The equation will be dimensionally correct.

b. The equation will be dimensionally correct except sometimes in cases when the right

hand side of the equation has more than one term.

c. The equation will not be dimensionally correct.

d. All constants of proportionality will be correct.

C3. How long has it been that scientists have accepted that the nucleus of the atom consists of

neutrons and protons? Think of your answers in terms of order of magnitude.

a. about a decade

b. about a century

c. about a thousand years

d. since Aristotle

C4. Consider the sine of any angle between 30° and 40°. If the angle were doubled, what would

happen to the sine of the angle?

a. It would double.

b. It would more than double.

c. It would increase but be less than double.

d. In different cases, it could do any of the above.

C5. There are other ways of expressing uncertainty besides significant figures. For example,

suppose a quantity is known to have a value between 20.4 and 20.0 and our best estimate of

the value is midrange at 20.2. We could write the number as 20.2 +/- 0.2 and say that the

number has a 1% uncertainty. We would also say it has 3 significant figures. If we square a

number with 1% uncertainty (i.e., 2 parts in about 200) and 3 significant figures, what

results?

a. A number with 1% uncertainty and 3 significant figures.

b. A number with 2% uncertainty and 3 significant figures.

c. A number with 2% uncertainty and 2 significant figures.

d. A number with 1% uncertainty and 2 significant figures.

1

Page 2

Chapter 1, Introduction

1.1 Standards of Length, Mass, and Time

1. Since 1983 the standard meter has been defined in terms of which of the following?

a. specific alloy bar housed at Sevres, France

b. wavelength of light emitted by krypton-86

c. distance from the Earth’s equator to the North Pole

d. the distance light travels in a certain fraction of a second

2. Since 1967 the standard definition for the second has been based on which of the following?

a. characteristic frequency of the cesium-133 atom

b. average solar day

c. sidereal day

d. Greenwich Civil Time

3. In mechanics, physicists use three basic quantities to derive additional quantities. Mass is one

of the three quantities. What are the other two?

a. length and force

b. power and force

c. length and time

d. force and time

4. The prefixes which are abbreviated p, n, and G represent which of the following?

a. 10-2, 10-6, and 1015

b. 10-9, 106, and 1010

c. 10-12, 10-9, and 109

d. 10-15, 10-6, and 1012

5. The ratio M/m of the prefixes M and m has what value?

a. 103

b. 106

c. 109

d. 1018

6. One year is about ________ seconds while one day is exactly ________ seconds.

a. 3.16 107, 86 400

b. 5.26 105, 86 400

c. 3.16 107, 8 640

d. 1.04 106, 36 000

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!"#$%&'()*(+,%#%-,.#/(012-/-3'-24(#.5(+,%#%-,.#/(67.#4-89

9. Masses are distributed in the <7-plane as follows: 10 kg at (2.0, 6.0) m, 4.0 kg at (2.0, 0.0) m,

and 6.0 kg at (0.0, 3.0) m. Where would a 20-kg mass need to be positioned so that the center

of gravity of the resulting four mass system would be at the origin?

a. (1.4, 3.9) m

b. (3.9, 1.4) m

c. (-1.4, -3.9) m

d. (-3.9, -1.4) m

10. A hoop of radius 1.0 m is placed in the first quadrant of an <7-coordinate system with its rim

touching both the <-axis and the 7-axis. What are the coordinates of its center of gravity?

a. (1.0, 1.0) m

b. (0.7, 0.7) m

c. (0.5, 0.5) m

d. Since there is nothing at the center of the hoop, it has no center of gravity.

11. Tasha has mass 20 kg and wants to use a 4.0-m board of mass 10 kg as a seesaw. Her friends

are busy, so Tasha seesaws by herself by putting the support at the system’s center of gravity

when she sits on one end of the board. How far is she from the support point?

a. 2.0 m

b. 1.0 m

c. 0.67 m

d. 0.33 m

12. An 80-kg man is one fourth of the way up a 10-m ladder that is resting against a smooth,

frictionless wall. If the ladder has a mass of 20 kg and it makes an angle of 60 with the

ground, find the force of friction of the ground on the foot of the ladder.

a. 7.8 x 102 N

b. 2.0 x 102 N

c. 50 N

d. 1.7 x 102 N

13. A 100-N uniform ladder, 8.0 m long, rests against a smooth vertical wall. The coefficient of

static friction between ladder and floor is 0.40. What minimum angle can the ladder make

with the floor before it slips?

a. 22

b. 51

c. 18

d. 42

113

Chapter 1, Introduction

CHAPTER 1

Conceptual Problems

C1. A room in a house has a floor area of 120 ft2. Which of the following is most likely the

approximate volume of the room?

a. 3 m3

b. 30 m3

c. 300 m3

d. 3 000 m3

C2. When SI units are plugged into an equation, it is found that the units balance. Which of the

following can we expect to be true for this equation?

a. The equation will be dimensionally correct.

b. The equation will be dimensionally correct except sometimes in cases when the right

hand side of the equation has more than one term.

c. The equation will not be dimensionally correct.

d. All constants of proportionality will be correct.

C3. How long has it been that scientists have accepted that the nucleus of the atom consists of

neutrons and protons? Think of your answers in terms of order of magnitude.

a. about a decade

b. about a century

c. about a thousand years

d. since Aristotle

C4. Consider the sine of any angle between 30° and 40°. If the angle were doubled, what would

happen to the sine of the angle?

a. It would double.

b. It would more than double.

c. It would increase but be less than double.

d. In different cases, it could do any of the above.

C5. There are other ways of expressing uncertainty besides significant figures. For example,

suppose a quantity is known to have a value between 20.4 and 20.0 and our best estimate of

the value is midrange at 20.2. We could write the number as 20.2 +/- 0.2 and say that the

number has a 1% uncertainty. We would also say it has 3 significant figures. If we square a

number with 1% uncertainty (i.e., 2 parts in about 200) and 3 significant figures, what

results?

a. A number with 1% uncertainty and 3 significant figures.

b. A number with 2% uncertainty and 3 significant figures.

c. A number with 2% uncertainty and 2 significant figures.

d. A number with 1% uncertainty and 2 significant figures.

1

Page 2

Chapter 1, Introduction

1.1 Standards of Length, Mass, and Time

1. Since 1983 the standard meter has been defined in terms of which of the following?

a. specific alloy bar housed at Sevres, France

b. wavelength of light emitted by krypton-86

c. distance from the Earth’s equator to the North Pole

d. the distance light travels in a certain fraction of a second

2. Since 1967 the standard definition for the second has been based on which of the following?

a. characteristic frequency of the cesium-133 atom

b. average solar day

c. sidereal day

d. Greenwich Civil Time

3. In mechanics, physicists use three basic quantities to derive additional quantities. Mass is one

of the three quantities. What are the other two?

a. length and force

b. power and force

c. length and time

d. force and time

4. The prefixes which are abbreviated p, n, and G represent which of the following?

a. 10-2, 10-6, and 1015

b. 10-9, 106, and 1010

c. 10-12, 10-9, and 109

d. 10-15, 10-6, and 1012

5. The ratio M/m of the prefixes M and m has what value?

a. 103

b. 106

c. 109

d. 1018

6. One year is about ________ seconds while one day is exactly ________ seconds.

a. 3.16 107, 86 400

b. 5.26 105, 86 400

c. 3.16 107, 8 640

d. 1.04 106, 36 000

2

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!"#$%&'()*(+,%#%-,.#/(012-/-3'-24(#.5(+,%#%-,.#/(67.#4-89

9. Masses are distributed in the <7-plane as follows: 10 kg at (2.0, 6.0) m, 4.0 kg at (2.0, 0.0) m,

and 6.0 kg at (0.0, 3.0) m. Where would a 20-kg mass need to be positioned so that the center

of gravity of the resulting four mass system would be at the origin?

a. (1.4, 3.9) m

b. (3.9, 1.4) m

c. (-1.4, -3.9) m

d. (-3.9, -1.4) m

10. A hoop of radius 1.0 m is placed in the first quadrant of an <7-coordinate system with its rim

touching both the <-axis and the 7-axis. What are the coordinates of its center of gravity?

a. (1.0, 1.0) m

b. (0.7, 0.7) m

c. (0.5, 0.5) m

d. Since there is nothing at the center of the hoop, it has no center of gravity.

11. Tasha has mass 20 kg and wants to use a 4.0-m board of mass 10 kg as a seesaw. Her friends

are busy, so Tasha seesaws by herself by putting the support at the system’s center of gravity

when she sits on one end of the board. How far is she from the support point?

a. 2.0 m

b. 1.0 m

c. 0.67 m

d. 0.33 m

12. An 80-kg man is one fourth of the way up a 10-m ladder that is resting against a smooth,

frictionless wall. If the ladder has a mass of 20 kg and it makes an angle of 60 with the

ground, find the force of friction of the ground on the foot of the ladder.

a. 7.8 x 102 N

b. 2.0 x 102 N

c. 50 N

d. 1.7 x 102 N

13. A 100-N uniform ladder, 8.0 m long, rests against a smooth vertical wall. The coefficient of

static friction between ladder and floor is 0.40. What minimum angle can the ladder make

with the floor before it slips?

a. 22

b. 51

c. 18

d. 42

113