Question

It is found out that a uniform beam 100cm long and of mass 95g can be balanced on a knife-edge when a 5g mass is hung 10cm from one end. How far is the knife-edge from the centre of the beam?

Answer 1

Let x be the distance from the center of the beam to the knife-edge.

The total mass of the beam is 95g, the mass hanging on one side is 5g, and the remaining mass on the other side is 95g - 5g = 90g.

Let the distance from the center of the beam to the 5g mass be 10cm. The distance from the center to the center of mass of the remaining 90g is x cm.

To balance the beam:
(5g)(10cm) = (90g)(x)

50 = 90x
x = 50/90
x = 5/9

Therefore, the knife-edge is located 5/9 cm from the center of the beam.