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

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west