Problems

Problems that are not marked with a star are considered the easiest to solve. Problems that are marked with a single star (*) are more difficult, while those marked with a double star (**) are the most difficult.
Note to Instructors: Most of the homework problems in this chapter are available for assignment via an online homework management program such as WileyPLUS or WebAssign, and those marked with the icon are presented in a guided tutorial format that provides enhanced interactivity. See Preface for additional details.
ssm Solution is in the Student Solutions Manual.
WWW Solution is available on the World Wide Web at . This icon represents a biomedical application.
Section 1.2 Units,
Section 1.3 The Role of Units in Problem Solving

| 1 | ssm The largest diamond ever found had a size of 3106 carats. One carat is equivalent to a mass of 0.200 g. Use the fact that 1 kg (1000 g) has a weight of 2.205 lb under certain conditions, and determine the weight of this diamond in pounds.

| 2 | Vesna Vulovic survived the longest fall on record without a parachute when her plane exploded and she fell 6 miles, 551 yards. What is this distance in meters?

| 3 | Bicyclists in the Tour de France reach speeds of 34.0 miles per hour (mi/h) on flat sections of the road. What is this speed in (a) kilometers per hour (km/h) and (b) meters per second (m/s)?

| 4 | Azelastine hydrochloride is an antihistamine nasal spray. A standard size container holds one fluid ounce (oz) of the liquid. You are searching for this medication in a European drugstore and are asked how many milliliters (mL) there are in one fluid ounce. Using the following conversion factors, determine the number of milliliters in a volume of one fluid ounce: , , and .

| 5 | ssm The mass of the parasitic wasp Caraphractus cintus can be as small as . What is this mass in (a) grams (g), (b) milligrams (mg), and (c) micrograms (μg)?

| 6 | A bottle of wine known as a magnum contains a volume of 1.5 liters. A bottle known as a jeroboam contains 0.792 U.S. gallons. How many magnums are there in one jeroboam?

| 7 | The following are dimensions of various physical parameters that will be discussed later on in the text. Here [L], [T], and [M] denote, respectively, dimensions of length, time, and mass.

| Dimension |  | Dimension
Distance (x) | [L] | Acceleration (a) | [L]/[T]2
Time (t) | [T] | Force (F) | [M][L]/[T]2
Mass (m) | [M] | Energy (E) | [M][L]2/[T]2
Speed (v) | [L]/[T] |  |

Which of the following equations are dimensionally correct?

a. |
b. |
c. |
d. |
e. |

| 8 | The volume of liquid flowing per second is called the volume flow rate Q and has the dimensions of [L]3/[T]. The flow rate of a liquid through a hypodermic needle during an injection can be estimated with the following equation:

The length and radius of the needle are L and R, respectively, both of which have the dimension [L]. The pressures at opposite ends of the needle are P2 and P1, both of which have the dimensions of [M]/{[L] [T]2}. The symbol represents the viscosity of the liquid and has the dimensions of [M]/{[L][T]}. The symbol stands for pi and, like the number 8 and the exponent n, has no dimensions. Using dimensional analysis, determine the value of n in the expression for Q.

* | 9 | ssm The depth of the ocean is sometimes measured in fathoms . Distance on the surface of the ocean is sometimes measured in nautical miles . The water beneath a surface rectangle 1.20 nautical miles by 2.60 nautical miles has a depth of 16.0 fathoms. Find the volume of water (in cubic meters) beneath this rectangle.

* | 10 | A spring is hanging down from the ceiling, and an object of mass m is attached to the free end. The object is pulled down, thereby stretching the spring, and then released. The object oscillates up and down, and the time T required for one complete up-and-down oscillation is given by the equation , where k is known as the spring constant. What must be the dimension of k for this equation to be dimensionally correct?
Section 1.4 Trigonometry

| 11 | You are driving into St. Louis, Missouri, and in the distance you see the famous Gateway-to-the-West arch. This monument rises to a height of 192 m. You estimate your line of sight with the top of the arch to be 2.0° above the horizontal. Approximately how far (in kilometers) are you from the base of the arch?

| 12 | The gondola ski lift at Keystone, Colorado, is 2830 m long. On average, the ski lift rises 14.6° above the horizontal. How high is the top of the ski lift relative to the base?

| 13 | ssm www A highway is to be built between two towns, one of which lies 35.0 km south and 72.0 km west of the other. What is the shortest length of highway that can be built between the two towns, and at what angle would this highway be directed with respect to due west?

| 14 | The drawing shows a person looking at a building on top of which an antenna is mounted. The horizontal distance between the person’s eyes and the building is 85.0 m. In part a the person is looking at the base of the antenna, and his line of sight makes an angle of 35.0° with the horizontal. In part b the person is looking at the top of the antenna, and his line of sight makes an angle of 38.0° with the horizontal. How tall is the antenna?

| 15 | The two hot-air balloons in the drawing are 48.2 and 61.0 m above the ground. A person in the left balloon observes that the right balloon is 13.3° above the horizontal. What is the horizontal distance x between the two balloons?

* | 16 | The drawing shows sodium and chloride ions positioned at the corners of a cube that is part of the crystal structure of sodium chloride (common table salt). The edge of the cube is 0.281 nm in length. Find the distance (in nanometers) between the sodium ion located at one corner of the cube and the chloride ion located on the diagonal at the opposite corner.

Problem 16

* | 17 | Interactive Solution 1.17 at presents a method for modeling this problem. What is the value of the angle in the drawing that accompanies problem 16?

* | 18 | A person is standing at the edge of the water and looking out at the ocean (see the drawing). The height of the person’s eyes above the water is , and the radius of the earth is . (a) How far is it to the horizon? In other words, what is the distance d from the person’s eyes to the horizon? (Note: At the horizon the angle between the line of sight and the radius of the earth is 90°.) (b) Express this distance in miles.

Problem 18

* | 19 | ssm Three deer, A, B, and C, are grazing in a field. Deer B is located 62 m from deer A at an angle of 51° north of west. Deer C is located 77° north of east relative to deer A. The distance between deer B and C is 95 m. What is the distance between deer A and C?

Hint:

(Consider the law of cosines given in Appendix E.)

** | 20 | A regular tetrahedron is a three-dimensional object that has four faces, each of which is an equilateral triangle. Each of the edges of such an object has a length L. The height H of a regular tetrahedron is the perpendicular distance from one corner to the center of the opposite triangular face. Show that the ratio between H and L is .
Section 1.6 Vector Addition and Subtraction

| 21 | (a) Two workers are trying to move a heavy crate. One pushes on the crate with a force , which has a magnitude of 445 newtons and is directed due west. The other pushes with a force , which has a magnitude of 325 newtons and is directed due north. What are the magnitude and direction of the resultant force applied to the crate? (b) Suppose that the second worker applies a force instead of . What then are the magnitude and direction of the resultant force applied to the crate? In both cases express the direction relative to due west.

| 22 | Consider the following four force vectors:

Which two vectors add together to give a resultant with the smallest magnitude, and which two vectors add to give a resultant with the largest magnitude? In each case specify the magnitude and direction of the resultant.

| 23 | ssm A circus performer begins his act by walking out along a nearly horizontal high wire. He slips and falls to the safety net, 25.0 ft below. The magnitude of his displacement from the beginning of the walk to the net is 26.7 ft. (a) How far out along the high wire did he walk? (b) Find the angle that his displacement vector makes below the horizontal.

| 24 | The drawing shows a triple jump on a checkerboard, starting at the center of square A and ending on the center of square B. Each side of a square measures 4.0 cm. What is the magnitude of the displacement of the colored checker during the triple jump?

Problem 24

| 25 | ssm www One displacement vector has a magnitude of 2.43 km and points due north. A second displacement vector has a magnitude of 7.74 km and also points due north. (a) Find the magnitude and direction of . (b) Find the magnitude and direction of .

| 26 | Two bicyclists, starting at the same place, are riding toward the same campground by two different routes. One cyclist rides 1080 m due east and then turns due north and travels another 1430 m before reaching the campground. The second cyclist starts out by heading due north for 1950 m and then turns and heads directly toward the campground. (a) At the turning point, how far is the second cyclist from the campground? (b) What direction (measured relative to due east) must the second cyclist head during the last part of the trip?

* | 27 | ssm www A car is being pulled out of the mud by two forces that are applied by the two ropes shown in the drawing. The dashed line in the drawing bisects the 30.0° angle. The magnitude of the force applied by each rope is 2900 newtons. Arrange the force vectors tail to head and use the graphical technique to answer the following questions, (a) How much force would a single rope need to apply to accomplish the same effect as the two forces added together? (b) How would the single rope be directed relative to the dashed line?

* | 28 | A jogger travels a route that has two parts. The first is a displacement of 2.50 km due south, and the second involves a displacement that points due east. (a) The resultant displacement has a magnitude of 3.75 km. What is the magnitude of , and what is the direction of relative to due south? (b) Suppose that had a magnitude of 3.75 km. What then would be the magnitude of , and what is the direction of relative to due south?

* | 29 | Before starting this problem, review Interactive Solution 1.29 at . Vector has a magnitude of 12.3 units and points due west. Vector points due north. (a) What is the magnitude of if has a magnitude of 15.0 units? (b) What is the direction of relative to due west? (c) What is the magnitude of if has a magnitude of 15.0 units? (d) What is the direction of relative to due west?

* | 30 | At a picnic, there is a contest in which hoses are used to shoot water at a beach ball from three directions. As a result, three forces act on the ball, , , and (see the drawing). The magnitudes of and are newtons and newtons. Using a scale drawing and the graphical technique, determine (a) the magnitude of and (b) the angle such that the resultant force acting on the ball is zero.

Section 1.7 The Components of a Vector

| 31 | ssm Vector points along the axis and has a magnitude of 100.0 units. Vector points at an angle of 60.0° above the axis and has a magnitude of 200.0 units. Vector points along the axis and has a magnitude of 150.0 units. Which vector has (a) the largest x component and (b) the largest y component?

| 32 | Your friend has slipped and fallen. To help her up, you pull with a force , as the drawing shows. The vertical component of this force is 130 newtons, and the horizontal component is 150 newtons. Find (a) the magnitude of and (b) the angle .

Problem 32

| 33 | An ocean liner leaves New York City and travels 18.0° north of east for 155 km. How far east and how far north has it gone? In other words, what are the magnitudes of the components of the ship’s displacement vector in the directions (a) due east and (b) due north?

| 34 | Soccer player #1 is 8.6 m from the goal (see the drawing). If she kicks the ball directly into the net, the ball has a displacement labeled . If, on the other hand, she first kicks it to player #2, who then kicks it into the net, the ball undergoes two successive displacements, and . What are the magnitudes and directions of and ?

Problem 34

| 35 | ssm The x vector component of a displacement vector has a magnitude of 125 m and points along the negative x axis. The y vector component has a magnitude of 184 m and points along the negative y axis. Find the magnitude and direction of . Specify the direction with respect to the negative x axis.

| 36 | The displacement vector has scalar components of and . The displacement vector has a scalar component of and a magnitude of . The displacement vector has a magnitude of and is directed at an angle of 36.9° above the axis. Two of these vectors are equal. Determine which two, and support your choice with a calculation.

* | 37 | To review the solution to a similar problem, consult Interactive Solution 1.37 at . The magnitude of the force vector is 82.3 newtons. The x component of this vector is directed along the axis and has a magnitude of 74.6 newtons. The y component points along the axis. (a) Find the direction of relative to the axis. (b) Find the component of along the +y axis.

* | 38 | The vector in the drawing has a magnitude 750 units. Determine the magnitude and direction of the x and y components of the vector , relative to (a) the black axes and (b) the colored axes.

** | 39 | ssm www The drawing shows a force vector that has a magnitude of 475 newtons. Find the (a) x, (b) y, and (c) z components of the vector.

Section 1.8 Addition of Vectors by Means of Components

| 40 | Multiple-Concept Example 9 reviews the concepts that play a role in this problem. As an aid in working this problem, consult Concept Simulation 1.1 at . Two forces are applied to a tree stump to pull it out of the ground. Force has a magnitude of 2240 newtons and points 34.0° south of east, while force has a magnitude of 3160 newtons and points due south. Using the component method, find the magnitude and direction of the resultant force that is applied to the stump. Specify the direction with respect to due east.

| 41 | ssm Consult Multiple-Concept Example 9 in preparation for this problem. A golfer, putting on a green, requires three strokes to “hole the ball.” During the first putt, the ball rolls 5.0 m due east. For the second putt, the ball travels 2.1 m at an angle of 20.0° north of east. The third putt is 0.50 m due north. What displacement (magnitude and direction relative to due east) would have been needed to “hole the ball” on the very first putt?

| 42 | Multiple-Concept Example 9 provides background pertinent to this problem. The magnitudes of the four displacement vectors shown in the drawing are , , , and . Determine the magnitude and directional angle for the resultant that occurs when these vectors are added together.

| 43 | Review Multiple-Concept Example 9 before beginning this problem. As an aid in visualizing the concepts in this problem, consult Concept Simulation 1.1 at . A football player runs the pattern given in the drawing by the three displacement vectors , , and . The magnitudes of these vectors are , , and . Using the component method, find the magnitude and direction of the resultant vector .

| 44 | A baby elephant is stuck in a mud hole. To help pull it out, game keepers use a rope to apply force , as part a of the drawing shows. By itself, however, force is insufficient. Therefore, two additional forces and are applied, as in part b of the drawing. Each of these additional forces has the same magnitude F. The magnitude of the resultant force acting on the elephant in part b of the drawing is twice that in part a. Find the ratio F/FA.

| 45 | As preparation for this problem, consult Concept Simulation 1.1 at . On a safari, a team of naturalists sets out toward a research station located 4.8 km away in a direction 42° north of east. After traveling in a straight line for 2.4 km, they stop and discover that they have been traveling 22° north of east, because their guide misread his compass. What are (a) the magnitude and (b) the direction (relative to due east) of the displacement vector now required to bring the team to the research station?

* | 46 | Three forces are applied to an object, as indicated in the drawing. Force has a magnitude of 21.0 newtons (21.0 N) and is directed 30.0° to the left of the axis. Force has a magnitude of 15.0 N and points along the axis. What must be the magnitude and direction (specified by the angle in the drawing) of the third force such that the vector sum of the three forces is 0 N?

* | 47 | ssm A sailboat race course consists of four legs, defined by the displacement vectors , , , and , as the drawing indicates. The magnitudes of the first three vectors are , , and . The finish line of the course coincides with the starting line. Using the data in the drawing, find the distance of the fourth leg and the angle .

* | 48 | The route followed by a hiker consists of three displacement vectors , , and . Vector is along a measured trail and is 1550 m in a direction 25.0° north of east. Vector is not along a measured trail, but the hiker uses a compass and knows that the direction is 41.0° east of south. Similarly, the direction of vector is 35.0° north of west. The hiker ends up back where she started, so the resultant displacement is zero, or . Find the magnitudes of (a) vector and (b) vector .

* | 49 | Interactive Solution 1.49 at presents the solution to a problem that is similar to this one. Vector has a magnitude of 145 units and points 35.0° north of west. Vector points 65.0° east of north. Vector points 15.0° west of south. These three vectors add to give a resultant vector that is zero. Using components, find the magnitudes of (a) vector and (b) vector .

* | 50 | Multiple-Concept Example 9 deals with the concepts that are important in this problem. A grasshopper makes four jumps. The displacement vectors are (1) 27.0 cm, due west; (2) 23.0 cm, 35.0° south of west; (3) 28.0 cm, 55.0° south of east; and (4) 35.0 cm, 63.0° north of east. Find the magnitude and direction of the resultant displacement. Express the direction with respect to due west.

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