AP Physics 1· difficulty 4/5
A uniform 4.0 m beam of mass 10 kg is supported by a pivot 1.0 m from one end. To balance, what mass should be hung at the closer end? ( m/s²; treat beam center at 2.0 m from short end)
40 kg
5 kg
20 kg
10 kg
Explanation
Beam center of mass is 2.0 m from each end, so it sits 1.0 m on the FAR side of the pivot. Beam weight produces N·m of torque about the pivot. The mass at the short end sits 1.0 m on the opposite side. Balance: N·m, so kg.
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