Notes: (i) Weight acts at the center of the ruler, at 50 cm. (ii) Weight and the 2 N force are right of the pivot and point down, so they both turn the ruler in the clockwise direction. Only the 4 N force turns the ruler anticlockwise. Also, the d in the formula is the distance between the force and the pivot, so that's 25 cm. (iii) Do a moment balance. The weight is 50 - 35 = 15 cm from the pivot and the 2 N force is 80 - 35 = 45 cm away. (iv) Let d be the distance between the pivot and the weight in m. Then (0.4 - d) must be the distance between the 4 N force and the pivot. (The 0.4 comes from the weight and 4 N being 0.4 m apart) Do another moment balance clockwise = anticlockwise(0.67 N)d = (4 N)(0.4 - d)d = 0.34 m = 34 cm Since d is the distance between the pivot and the weight, 50 cm - 34 cm = 16 cm should be the new location of the pivot.
