A uniform pencil AB weighing 40g can be balanced horizontally ona knife edge at 2 cm bfrom the end A when a mass of 60 g is hung from this end.what is the length of the pencil?
To find the length of the pencil, we can use the principle of moments. The principle of moments states that for an object in equilibrium, the sum of the clockwise moments about any point is equal to the sum of the anticlockwise moments about the same point.
In this case, we can take moments about the knife edge. Let's assume the length of the pencil is x cm.
The moment of the 60g mass about the knife edge is given by the formula: Moment = Weight x Distance
The moment of the pencil about the knife edge is given by the formula: Moment = Weight x Distance
Since the pencil is balanced on the knife edge, the sum of the clockwise moments is equal to the sum of the anticlockwise moments:
(60g x 2cm) = (40g x x cm)
Simplifying the equation:
120 g·cm = 40 g·cm
Dividing both sides by 40g:
3 cm = x
Therefore, the length of the pencil is 3 cm.