Practice Problems 7.1.1 — Static Equilibrium 1. Two rugby players pull on a ball in the directions shown in Figure 10.1.4. What is the magnitude of the force that must be exerted by a third player, to achieve translational static equilibrium of the ball?
F1 = 50.0 N
F2 = 80.0 N Figure 7.1.4
2. A 50.0 kg mass is supported by a rope. When a horizontal force is used to hold the mass at an angle θ with the vertical, the tension in the rope is 850.0 N. What is angle θ?
tension force FT = 850 N
θ
m = 50.0 kg Figure 7.1.5
3. (a) A traffic light is suspended midway between two supports, as shown in Figure 7.1.6. If the mass of the traffic light is 60.0 kg, what is the tension in the cord between A and B?
A
B
82°
82°
mass = 60.0 kg Figure 7.1.6
(b) Explain why it is not possible to have the cord absolutely straight between the two supports in this static equilibrium situation.
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Chapter 7 Torque and Rotational Motion 295