Question

A 20N metal block is suspended by a spring balance. A beaker containing some water is placed on a weighing machine which reads 40N. The spring balance is lowered such that that the block gets immersed in the water. The spring balance now reads 16N. The reading of the weighing machine will be

a)36N b)60N c)44N d)56N

Answer 1

Initial reading =20N

Final reading =16N

Decreased weight=20-16=4N(upward direction)

Now, weight recorded by weighing machine=36N

Therefore, the reading of the weighing machine will be 36+4=40N (downward direction) (acc.to newton’s third law)