The potential energy for a force field $$\mathbf{F}$$ is given by $$u(x, y)=\cos (x+y)$$. The force acting on a particle at position given by co-ordinates $$(0, \pi / 6)$$ is
A direct current of $$10 \mathrm{~A}$$ is superimposed on an alternating current $$i=10 \sin \omega t$$ flowing through the wire. The effective value of the resulting current will be.
The $$x$$-$$t$$ graph of a particle performing simple harmonic motion is shown in the figure. The acceleration of the particle at $$t=2. \mathrm{~s}$$ is
A vessel is half filled with a liquid of refractive index $$\mu$$. The other half of the vessel is filled with an immiscible liquid of refractive index $$2 \mu$$. The apparent depth of the vessel is $$50 \%$$ of the actual depth. Then $$\mu$$ is