A window in Patty O Cover house is stuck She takes an 8inch

A window in Patty O\' Cover house is stuck. She takes an 8-inch screwdriver to pry open the window. If the screwdriver rests on the sill (fulcrum) 3 inches from the window and Patty O Cover has to exert a force of 10 pounds on the other end to pry open the window, how much force was the window exerting? A 35-pound weight is 2 feet from the fulcrum, and a 75-pound weight on the same side is 10 feet from the fulcrum. If a weight on the other end 6 feet from the fulcrum balances the first two, how much does it weigh? A lever 10 feet long has a 100-pound weight on one end and a 150-pound weight on the other. If the fulcrum is in the center, in what location must an 80-pound weight be placed so that the lever will balance? Batman and Robin go out to play. Batman, who weighs 90 pounds, sits on one end of a 14-foot teeter-totter. Its balance point is at the center of the board. Robin, who weighs 120 pounds, climbs on the other end and slides toward the center until they balance. What is Robin\'s distance from her end of the teeter-totter when they balance?

Solution

8.

35 pound is placed at 2 ft from fulcrum in right side

75 pound is placed at 10 ft from fulcrum in right side

Suppose X pound is placed at 6 ft from fulcrum in left side

Using torque balance

35*2 + 75*10 = X*6

X = (70 + 750)/6 = 820/6 = 136.67 pound.

9.

100 pound is placed at 5 ft from fulcrum in right side

150 pound is placed at 5 ft from fulcrum in left side

80 pound is placed at x ft from fulcrum in any direction

suppose 80 pound is placed in left direction

then using torque balance

100*5 = 150*5 + 80*x

80*x = 500 - 750

x = -250/80 = -3.125 ft

-ve sign means 80 pound should be placed in right side at 3.125 ft from fulcrum.