posted by Sami .
Suppose you need to measure the mass of an object, but have only a 7-kg standard mass and a meter stick. Place a knife edge under the 50-cm mark of the meter stick. Then put the 7-kg standard mass at the 39.1-cm mark and place the object so as to balance the standard mass. If the system is balanced when the object is at the 85.9-cm mark, find the unknown mass.
7*10.9 = M*35.9
Solve for M
The two numbers above are the distances of the masses from the fulcrum at the 50 cm midpoint location.