The 600-N ball shown is suspended on a string AB and rests against the frictionless vertical wall. The string makes an angle of
30° with the wall. The line AB goes through the center of the ball, and the contact point with the wall is at the same vertical height as the center of the ball. The ball presses against the wall with a force of magnitude:
There are 4 hydrogens on the right side , and 2 hydrogens on the left per molecule of . To get the same number of hydrogens on both sides, the coefficient should be 2.
(Then the number of oxygens will be consistent, since contributes 2 oxygens, and so does .)