Chapter 7 Answer Key: Equilibrium and Newton’s First Law
Chapter 7: Equilibrium & Newton’s First Law (Key)
7.1 Right Angle Trigonometric Functions
1. 0.743145
2. 0.484810
3. 0.906308
4. 0.484810
5. 0.194380
6. 1.53986
7. 0.190810
8. 0.544639
9. 29°
10. 39°
11. 50°
12. 52°
13. 33.3°
14. 8.9°
15. 41.0°
16. 81°
17. z = 27.36 (≈ 27), ø = 26.6° (≈ 27°)
18. y = 19.6 (≈ 20), ø = 44.4° (≈ 44°)
19. x = 16, ø = 53.1° (≈ 53°)
20. x = 21.2 (≈ 21), y = 13.2 (≈ 13)
21. x = 892 (≈ 890), y = 803 (≈ 800)
22. z = 242 (≈ 240), ø = 24.4° (≈ 24°)
23. x = 9.8, y = 6.9
24. x = 37.6 (≈ 38), y = 42.6 (≈ 43)
25. z = 25, ø = 53.1° (≈ 53°)
26. y = 75, ø = 36.9° (37°)
27. y = 4, ø = 53.1° (≈ 53°)
28. y = 11.1 (≈ 11), z = 27.4 (≈ 27)
29. z = 28.6 (≈ 29), ø = 44.4° (≈ 44°)
30. y = 19.6 (≈ 20), ø = 44.4° (≈ 44°)
31. y = 8.9, ø = 41.8° (≈ 42°)
32. x = 35, y = 61
7.2 Vector Resolution into Components
1. vy = 25.4 (≈ 25), vx = 40.7 (≈ 41)
2. vy = 11, vx = 19.1 (≈ 19)
3. Fy = 15, Fx = 28.3 (≈ 28)
4. Fy = 53.7 (≈ 54), Fx = 79.6 (≈ 80)
5. ay = 13.6, ax = 15.2
6. ay = 22.0, ax = 45.1
7. vy = 25.4 (≈ 25), vx = 40.7 (≈ 41)
8. vy = 11, vx = 19.1 (≈ 19)
9. Fy = 15, Fx = 28.3 (≈ 28)
10. Fy = 53.7 (≈ 54), Fx = 79.6 (≈ 80)
11. ay = 13.6, ax = 15.2
12. ay = 22.0, ax = 45.1
7.3 Static Equilibrium (Concurrent Forces)
1. Ty = 980 N2. Ty = 5.0 N
3. T1 = 228 N (≈ 230 N), T2 = 541 N (≈ 540 N)
4. T1 = 89.2 N (≈ 89 N), T2 = 261 N (≈ 260 N)
5. T1 = 769 N (≈ 770 N), T2 = 663 N (≈ 660 N)
6. T1 = 8502 N (≈ 8500 N), T2 = 5557 N (≈ 5600 N)
7. T = 6685 N ( ≈ 6700 N), FC = – 5268 N (≈ – 5300 N)
8. FC = – 14 300 N (≈ – 14 000 N)
7.4 Limits of a Cable
(i) 0.49 m from the top (ii)