Question

A glass plate of length `0.1 m`, breadth `15 xx 10^(3) m` and thickness `2 xx 10^(-3)m` weighs `8 xx 10^(-3) kg` in air, it is held vertically with its longer side horizontal and its lower half immersed in water. If the surfaces tension of water is `72 xx 10^(-3) N//m`, the apparent weight of the plate is `79.4 lambda xx 10^(-3) N`. Then find `lambda`

Answer 1

Correct Answer - `1`
`w_(app) = mg - f_(B) + 2T (l + T) = 8 xx 10^(-3) xx 10 - (0.1 xx 15 xx 10^(-3) xx 2 xx 10^(-3) )/(2) xx 10^(3) xx 10 + 2 xx 72 xx 10^(-3) (0.1 + 2 xx 10^(-3))= 79.4 xx 10^(-3) N`