The free surface of oil in a tanker, at rest, is horizontal if the tanker starts ac celerating the free surface will be titled by an angle `theta.` If the ac celeration is a ` ms^(-2)` what will be the slope of the free surface ?

Explanation

When the tanker accelerates along the positive X-direction, the oil near the back rises up. The free surface of the water is inclined. The tangential force on any part of the surface oil is zero.
Let p be the density of oil. Since the free surface of the fluid is such that the tangential force on it is zero. Hence during accelerated motion, the component of acceleration along the surface will be balanced by the component of the weight along the surface. i.e. `p alpha cos theta=pg sin theta`
`or tan theta=a/g`