The elastic potential energy of a strained body is

A body floats with $$\frac{1}{n}$$ of its volume keeping outside of water. If the body has been taken to height $$\mathrm{h}$$ inside water and released, it will come to the surface after time t. Then

Water is filled in a cylindrical vessel of height $$\mathrm{H}$$. A hole is made at height $$\mathrm{z}$$ from the bottom, as shown in the figure. The value of z for which the range (R) of the emerging water through the hole will be maximum for

A metal plate of area $$10^{-2} \mathrm{~m}^2$$ rests on a layer of castor oil, $$2 \times 10^{-3} \mathrm{~m}$$ thick, whose coefficient of viscosity is $$1.55 \mathrm{~Ns} \mathrm{~m}^{-2}$$. The approximate horizontal force required to move the plate with a uniform speed of $$3 \times 10^{-2} \mathrm{~ms}^{-1}$$ is