The weight of three iron rods

In a Kundt's tube , the length of the iron rod is 1 m . The stationary waves frequency 2500 Hz are produced in it. The velocity of sound in iron is

If the weight of A is 60kg, weight of B is 45kg and weight of C is 54kg, then what is the average weight of three persons?

Three weights W , 2 W and 3 W are connected to identical springs suspended from a rigid horizontal rod. The assembly of the rod and the weights fall freely. The positions of the weights from the rod are such that

Three weights w, 2w and 3w are connected to identical spring suspended from a rigid horizontal rod. The assembly of the rod and the weights fall freely. The positions of the weight from the rod are such that

Four rods made of iron, wood, paper, and plastic are connected by a straight metallic rod, as shown in the given figure. The rods are heated by a hot filament placed near them. After sometime, it is observed that the temperature of the iron rod is more than that of the other three rods. Heat transfer whitin the rods takes place by