Final answer:
To balance the meter rule, the 50g weight should be suspended at the 25cm mark on the meter rule.
Step-by-step explanation:
To balance the uniform meter rule, we need to consider the principle of moments. The principle of moments states that for an object to be in equilibrium, the sum of the clockwise moments about any point must be equal to the sum of the anticlockwise moments about the same point. The moment of a force can be calculated by multiplying the force by the perpendicular distance from the point to the line of action of the force.
In this case, the meter rule is pivoted at the 60 cm mark, so the distance from the pivot to the 50g weight is 60 cm. Let's assume the distance from the pivot to the 120g meter rule is x. To balance the meter rule, the clockwise moment due to the weight of the meter rule (120g) must equal the anticlockwise moment due to the weight of the 50g weight. Therefore, we can set up the equation: 120g*x = 50g*60cm.
Simplifying the equation, we get x = (50g*60cm)/120g = 25cm. Therefore, the 50g weight should be suspended at the 25cm mark on the meter rule for it to balance horizontally.