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Worksheet: Rotational Equilibrium

Q1:

A uniform seesaw is balanced on a fulcrum located 3.0 m from the left end, as shown. The smaller boy on the right has a mass of 40 kg and the bigger boy on the left has a mass 80 kg. What is the mass of the board?

Q2:

The uniform seesaw is balanced at its center of mass, as shown. The smaller boy on the right has a mass of 40 kg. What is the mass of his friend?

Q3:

To get up on the roof of a house, a person with a mass of 70.0 kg places a 6.00-m-long aluminum ladder against the house on a concrete pad, with the base of the ladder 2.00 m from the house. The ladder rests against a plastic rain gutter, which has negligible friction with the ladder. The ladder’s mass is 10.0 kg, and its center of mass is 2.00 m from the ladder’s bottom. The person is standing 3.00 m from the bottom of the ladder.

Find the magnitude of the normal reaction force on the base of the ladder.

Find the friction force on the base of the ladder.

Q4:

A homogeneous cube of weight 100 kN sits on a horizontal plane. Determine the minimum force F acting on the upper top edge of the cube, parallel with its surface, that is required to tip the block over.

Q5:

A uniform 40.0-kg scaffold of length 6.0 m is supported by two light cables, as shown in the figure. An 80.0-kg painter stands 1.0 m from the left end of the scaffold, and his painting equipment is 1.5 m from the right end. The tension in the left cable is twice that in the right cable.

Find the tension in the right cable.

Find the tension in the left cable.

Find the mass of the equipment.

Q6:

When the structure shown is supported at point 𝑃 , the structure is in equilibrium. The weight of the structure is negligible.