In the video, the torque due to the mass of the plank is used in the calculations. For this question, ignore the mass of the board. Rank, from largest to smallest, the mass m needed to keep the board from tipping over. To rank items as equivalent, overlap them.

D, A & B, C, E

Explanation:

In each problem, sum the torques about the edge of the table.

A) ∑τ = Iα

mg (-1.5 m) + (100 kg) g (1.5 m) = 0

m = 100 kg

B) ∑τ = Iα

mg (-0.75 m) + (100 kg) g (0.75 m) = 0

m = 100 kg

C) ∑τ = Iα

mg (-1.5 m) + (100 kg) g (0.75 m) = 0

m = 50 kg

D) ∑τ = Iα

mg (-1.5 m) + (200 kg) g (1.5 m) = 0

m = 200 kg

E) ∑τ = Iα

mg (-1.5 m) + (100 kg) g (0.5 m) = 0

m = 33.3 kg

the correct choice is a .

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your answer is c! hope this : )