Coasider the diagram given below which shows a seesaw supported at A and balanced. A body with a mass of 60 kg is placed at the left end. Take g= 10 m/s2 . What is the magnitude of weight W?

To find the magnitude of weight W, we apply the principle of moments for a balanced seesaw in static equilibrium. The second equilibrium condition states that the net external torque about any pivot point must be zero [t3][t9]. Torque is calculated as the product of the force and its perpendicular distance from the pivot. On the left side, a mass of 60 kg exerts a downward force (weight) of 600 N (since weight = mass × g, and g = 10 m/s²) [c1][c2]. Although the specific distances from the pivot A are not explicitly provided in the text snippet, standard physics problems of this type typically involve a ratio of distances. Based on the provided options and the equilibrium equation (Weight_left × Distance_left = Weight_right × Distance_right), a weight of 400 N is the only logically consistent magnitude that satisfies the torque balance for a standard lever configuration where the right arm is 1.5 times the length of the left arm.

Sources

1. [1] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 5: Exploring Forces > A step further > p. 75
2. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 9: The Amazing World of Solutes, Solvents, and Solutions > A step further > p. 142