$(3)$ The rectangular tank shown in Figure $3$ below is $1\mathrm{.}2$ m deep and $2$ m long is used to convey water up a ramp inclined at an angle $\backslash (\backslash$theta$=30^\{\backslash$circ$\}\backslash )$ to the horizontal. Calculate the inclination of the water surface to the horizontal when

$($a$)$ the acceleration parallel to the slope on starting from bottom is $\backslash (4\mathrm{.}5\backslash$mathrm$\{$~m$\}/\backslash$mathrm$\{$s$\}^\{2\}\backslash ),$

$($b$)$ the deceleration parallel to the slope on starting from bottom is $\backslash (4\mathrm{.}5\backslash$mathrm$\{$~m$\}/\backslash$mathrm$\{$s$\}^\{2\}\backslash ),$

If no water is to be spilt during the journey, what is the greatest depth of water permissible in the tank when it is at rest?

Figure $3$