FIGURE 6-12
-Two masses are connected by a string which goes over an ideal pulley as shown in Figure 6-12. Block A has a mass of 3.0 kg and can slide along a smooth plane inclined 30° to the horizontal. What is the mass of block B if the system is in equilibrium?
A) 1.5 kg
B) 3.0 kg
C) 2.6 kg
D) 3.5 kg
E) 6.0 kg

Question

FIGURE 6-12 
-Two masses are connected by a string which goes over an ideal pulley as shown in Figure 6-12. Block A has a mass of 3.0 kg and can slide along a smooth plane inclined 30° to the horizontal. What is the mass of block B if the system is in equilibrium?
A) 1.5 kg 
B) 3.0 kg 
C) 2.6 kg 
D) 3.5 kg 
E) 6.0 kg

Quizplus · Accepted Answer

The tension in the string is equal to the weight of block B. The component of the weight of block A parallel to the plane is equal to the tension in the string. Therefore, the mass of block B is equal to the mass of block A times the sine of the angle of the plane.$$m_B = m_A \sin 	heta$$$$m_B = 3.0 	ext{ kg} \sin 30° = 1.5 	ext{ kg}$$

FIGURE 6-12 -Two Masses Are Connected by a String Which Goes Over