Part a 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.

Answer: Think of this as a seesaw. Balance the right hand torques (clockwise) with the left hand (counterclockwise) torques 1.5m = 1.5*100 = 150 a) 1.50m = 1.50*100 = 150 a) = > m = 150/1.5 = 100 a) 0.75m = 0.75*100 = 75 b) = > m = 75/0.75 = 100 b) 1.50m = 0.75*100 = 75 c) = > m = 75/1.5 = 50 c) 1.50m = 1.50*200 = 300 d) = > m = 300/1.5 = 200 d) 1.50m = 0.50*100 = 50 e) = > m = 50/1.5 = 100/3 e) So the order from heaviest to lightest is d, a, b, c, e