Question

A 10 Kg Wooden Plank Of 1 M Length Is In Equilibrium Attached To A Hinge On The Left

Answer 1

Answer:

Buoyancy force will act on the center of submerged part of plank ,

distance from O is d=

2cosθ

0.5

distance of center of mass from is a=1/2=0.5m.

let the cross section be A and density of water be ρ

weight of plank is w=1×A×0.5ρ×g,}

writing torque about O

we get Bdcosθ=W×0.5×cosθ

we get cos

2

θ=1/2

so

cos

2

θ

1

=2