Complete the following sentences:
Two balls, one of iron and the other of aluminium experience the same upthrust when dipped completely in water if…………………….

Answer

To complete the sentence: "Two balls, one of iron and the other of aluminium experience the same upthrust when dipped completely in water if..."

**Step 1: Understand Upthrust**
Upthrust, or buoyant force, is the upward force exerted by a fluid on an object submerged in it. According to Archimedes' principle, this force is equal to the weight of the fluid displaced by the object.

**Step 2: Consider the Conditions for Same Upthrust**
For two objects to experience the same upthrust, they must displace the same volume of fluid. Since the upthrust is dependent on the volume of fluid displaced, it is essential to ensure that both objects have the same volume when submerged.

**Step 3: Relate Volume to Weight of Displaced Water**
If both balls (iron and aluminium) have the same volume, they will displace the same amount of water when submerged. Consequently, the weight of the water displaced by each ball will be equal.

**Step 4: Conclude the Statement**
Thus, the complete sentence would be: "Two balls, one of iron and the other of aluminium experience the same upthrust when dipped completely in water if they have the same volume."