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An object of mass 400g and density 600kgm-3 is su...

An object of mass 400g and density 600kgm-3 is suspended with a sting so that half of it is immersed in paraffin of density 900kgm-3. The tension in the string is

A.

1.0N

B.

3.0N

C.

4.0N

D.

5.0N

Correct answer is B

volume of object = \(\frac{400 \times 10^{-2}}{600}\)

= 0.00067m3

volume of paraffin displaced = \(\frac{1}{2}\) x 0.00067

= 0.00034m3

mass of paraffin = 900 x 34 x 10-5

= 0.3kg

weight of paraffin = 0.3 x 10

= 3N = upthrust = tension in the string