Appendix F: Answers to Problems

Chapter1
Chapter2
Chapter3
Chapter4
Chapter5
Chapter6
Chapter7
Chapter8
Chapter9
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Chapter 1:

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1. Fastball t = 0.45 sec; curveball t = 0.68 sec

2. t = 0.2 sec

4. u = 5.45 m/sec = 12mph

5. Johnson u = 95.01 ft/sec; Mueller u = 94.77 ft/sec

6. a. At the 70 meter mark

7. a = 3 ft/sec²

d = 150 ft

8. b. Distance traveled while reacting = 70.4 ft

c. Distance traveled while stopping = 193.6 ft

d. Total distance needed to stop = 264 ft

9. a. d = 45 m

b. t = 3 seconds

c. t = 6 seconds

d. v = 30 m/sec, down

10. t = 1 sec: d = 15 m, v = 10 m/sec, up

t = 2 sec: d = 20 m, v = zero

t = 3 sec: d = 15 m, v = 10 m/sec, down

t = 4 sec: d = 0, v = 20 m/sec, down

t = 5 sec: d = -25 m, v = 30 m/sec, down

11. v = 32 ft/sec

t = 1 sec

12. a. t = 0.47 sec

b. t = 0.35 sec

Chapter 2:

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1. t = 0.5 seconds, x = 2.0 meters

2. t = 4 seconds, y = 80 meters

3. y = 4 ft

4. a. y = 0.81 ft

b. y = 3.24 ft

c. y = 2.43 ft

5. a. v_Ix = 86.6 m/sec b. v_Ix = 70.7 m/sec c. v_Ix = 50 m/sec

v_Iy = 50 m/sec v_Iy = 70.7 m/sec v_Iy = 86.6 m/sec

6. a. v_x = 2.4 m/sec

b. v_y = 6.6 m/sec

c. y = 2.2 meters = 7.1 ft

7. a. v_Ix = 40 m/sec, v_Iy = 30 m/sec

b. y = 45 meters

c. t = 3 seconds

d. v = 40 m/sec in the horizontal direction

e. a = g = 10 m/sec², down

f. t = 6 seconds

g. R = 240 meters

8. R = 517 ft = 172 yd

9. a. h = 41 ft

b. h = 176 ft

10. v_I = 121 ft/sec

11. v = 38 ft/sec

Chapter 3:

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1. F = 200 N

2. W = 170 N

3. m = 7 slugs

6. F = 35 lb

7. m = 5 slugs, W = 160 lb

8. a. a = 111 m/sec²

b. F = 7770 N = 1746 lb

c. F = 1665 N = 374 lb

9. a = 6 m/sec2

b. W = 500 N

c. Force parallel = 300 N

d. R = 400 N

e. Zero

10. a. F_net = 25 N, right

Block accelerates

b. F_net = 0

Block moves with constant acceleration

c. F_net = 25 N, left

Block decelerates

11. W = 500 lb

12. Kinetic frictional force, the normal force, and the puck’s weight.

13. a. F_s = 5 N

b. R = 20 N

c. m_s = 0.25

14. F = 51.8 lb

15. a. F = 51.8 lb

b. F = 100 lb

Chapter 4:

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1. The 20 kg object

2. a. Change in momentum = 6 N•sec

b. Impulse = 6 N•sec

c. F = 120 N = 27 lb

3. a. Change in momentum = 15 N•sec

b. Impulse = 15 N•sec

c. F = 6000 N = 1350 lb

4. v = 20 mph

5. a. m = 5 slugs

b. v = 8 ft/sec

c. Impulse = 40 lb•sec

d. t = 0.0125 sec

e. F = 3200 lb

6. v = 9.6 ft/sec

7. v = 5.3 ft/sec

9. h = 0.58 m

Chapter 5:

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1. Work = 350 J. If t = 1 sec, P = 350 Watts; if t= 10 sec, P = 35 Watts

2. Work = 4000 J

3. Work = 9000 J, t = 9 seconds

4. a. 87 ft•lbs

b. 87 ft•lbs

c. 522 lbs

5. a. Work = 625 J

b. Work = 1600 J – 625 J – 975 J

6. d = 200 feet

7. h – 121 feet

8. v = 21 ft/sec

9. v = 10 m/sec

10. h = 0.45 m

Chapter 6:

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1. q = 6p radians = 1080 degrees

2. q = 2 radians = 0.32 revolutions = 114.6 degrees

3. w = 3.33 rev/sec = 20.9 rad/sec

4. q = 0.56 rev

5. a = -0.022 rev/sec², q = 7.28 rev

6. w_I = 1.2 rev/sec = 72 rpm

7. w_F = 20 rad/sec, q= 100 rad = 16 rev

8. s = 40 m, v = 8 m/sec, a = 0.8 m/sec²

9. Nine-iron: v = 15 ft/sec

Driver: v = 20 ft/sec

10. w = 57 rad/sec = 9 rev/sec

11. F = 209.5 N

12. F = 8000 N = 1798 lbs

13. a = 12.5 m/sec²; F = 875 N

14. w = 3.17 rad/sec = 0.5 rev/sec

Chapter 7:

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1. a. 600 ft•lb

b. 1400 N•m

c. 300 ft•lb

d. zero

2. 4 feet from the center of the seesaw.

3. x = 4 feet

4. Force exerted by the Achilles = 514 lb; Force on the tibia = 714 lb

5. F = 100 lb

6. W = 6 lb

8. a. 33 lb

b. 67 lb

c. 20 lb

9. I = 0.5 kg/m²; Torque = 4 N•m

10. a. I = 10 kg•m²

b. I = 26.7 kg•m²

c. w = 0.75 rev/sec

12. a. I = 600 kg•m²

b. w = 0.75 rev/sec

13. a. I =0.045 kg•m²

b. w = 26.7 rad/sec

c. KE_ROT = 16 J

d. KE_TRANS = 40 J

e. KE_TOT = 56 J

14. h = 1.6 m

Chapter 8:

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1. m = 3800 g; W = 8.36 lb

2. d = 7.93 g/cm³

3. If your mass is 70 kg, then your volume would be 70 liters.

4. If your volume is 70 liters, then 14.3 similar people could fit into a 1 m³ box.

5. Without a helmet the pressure is 50 times greater.

6. P = 13 N/cm²

7. P = 5.7 lb/in²

8. P = 161.9 Atmospheres = 2380 lb/in²

9. The bubbles become larger.

10. h = 0.5 m

11. P = 19,000 N/m² = 144 mm of mercury

12. This is the same level as your heart.

13. h = 0.76 m = 76 cm = 30 inches

14. h = 10 meters

15. F = 50 lb

16. F = 20 N

17. a. W = 700 N

b. V = 0.067 m³

c. V = 0.067 m³

d. m = 67 kg

e. BF = 670 N

f. Apparent weight = 30 N = 6.4 lb

18. 92 percent. Less of the iceberg would be submerged in seawater.

Chapter 9:

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1. a. v = 12 m/sec

b. P = 132, 500 N/m²

c. same

2. v = 12.5 m/sec

3. m/t = 88 g/sec

4. v = 26.5 cm/sec

5. v = 41.4 cm/sec

6. P1 – P2 = 53.6 N/m²

8. a. P1 – P2 = 8060 N/m²

F = 64,480 N = 14, 490 lbs