CBSE Class 10 Answered

3. 40 gm more than R

When the solid is lowered, and sunk fully in water somel of it's weight is transfered to water, and hence onto the pan. Some of the weight, since some will be balanced by the buoynacy force.

Buoyancy force = (40 cm³)(1 gm/cm³)(980 cm/s²)

So the total mass (weight) 80 gm, but buoyancy cancels out 40 gm. So net increases on the water with beaker side of pan is 40 gm. That means we have to put another R, which has to be more than previous R by 40 gm.

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