A Pulley with Radius R Is Free to Rotate on a Horizontal

question 24

Multiple Choice

A pulley with radius R is free to rotate on a horizontal fixed axis through its center. A string passes over the pulley. Mass m₁ is attached to one end and mass m₂ is attached to the other. The portion of the string attached to m₁ has tension T₁ and the portion attached to m₂ has tension T₂. The magnitude of the total external torque, about the pulley center, acting on the masses and pulley, considered as a system, is given by:

• A) \(\mid\)m₁ - m₂\(\mid\)gR
• B) (m₁ + m₂)gR
• C) \(\mid\)m₁ - m₂\(\mid\)gR + (T₁ + T₂)R
• D) (m₁ + m₂)gR + (T₁ - T₂)R
• E) \(\mid\)m₁ - m₂\(\mid\)gR + (T₂ - T₁)R

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