A 5.0 m wide rectangular channel carries a discharge of $10 \mathrm{~m}^3 / \mathrm{s}$ at a depth of 1.5 m under uniform flow. To produce critical flow conditions without affecting the upstream conditions, the channel bottom elevation should be raised (in m ) by _________ (rounded off to 2 decimal places).

Assume that there is no loss of head at the raise, kinetic energy correction factor is 1.0 , and acceleration due to gravity is $9.81 \mathrm{~m} / \mathrm{s}^2$.

If the horizontal distance between a staff point and the point of observation is $d$, the error due to the curvature of earth is proportional to

If the quadrantal bearing of a line is N30,,aW, then the whole circle bearing of the line is

In levelling between two points A and B on the opposite banks of a river, the readings are taken by setting the instrument both at $A$ and $B$, as shown in the table. If the $R L$ of $A$ is 150.000 m , the $R L$ of $B$ (in m ) is __________ (rounded off to 3 decimal places).

Level position	Staff readings
	A	B
A	1.800	1.350
B	1.450	0.950