A vessel with water is placed on a weighing pan and reads 600g. Now a ball of 40 g and density 0.8 g/cc is sunk into the water with a pin as shown in figure, keeping it sunk. The weighing Pan will show a reading.

The density of ball is less than that of water. Therefore the ball will try to go upward due to up thrust acting on it. The force required to hold it in position is 

F = up thrust = Veg = $\left(\frac{40}{0.8}\right)\times 1\times 10 \therefore \mathrm{Rading} \mathrm{is} 600+50=650\mathrm{g}$