Question

1. the weight of a solid in air is 5.0n, when it is fully immersed in a liquid of density 800kgm-3 its weight is 4.04n. determine the upthrust in the liquid. (2 marks)

Explanation:

Step1: Find mass of the solid

Mass $m = \frac{Weight}{g} = \frac{5.0N}{9.8m/s^2} \approx 0.510kg$

Step2: Find volume of the solid

Volume $V = \frac{m}{
ho_{solid}}$? No, wait—upthrust $U =
ho_{liquid}gV$. First, $U = Weight_{air} - Weight_{liquid} = 5.0N - 4.04N = 0.96N$

Step3: Verify with Archimedes' principle

$U =
ho_{liquid}gV$, but we can directly calculate upthrust as the weight difference.

Answer:

0.96N