In case of well of death which is a vertical cylindrical wall of radius ' $r$ ' inside which vehicle is driven in horizontal circles. If ' $m$ ' is mass of vehicle, ' $V$ ' is the velocity and ' $\mu_s$ ' is the coefficient of static friction between the wheels of vehicle and walls then correct relation is [ $\mathrm{g}=$ acceleration due to gravity]
In an oscillating LC circuit, the maximum charge on the capacitor is ' $Q$ '. When the energy is stored equally between the electric and magnetic fields, the instantaneous charge on the capacitor ' $q$ ' is
Two particles execute S.H.M. of same amplitude and frequency along the same straight line path. They pass each other when going in opposite directions, each time their displacement is half the amplitude. The phase difference between them is $\left(\sin 30^{\circ}=0 \cdot 5\right)$
The pitch of whistle of an engine appears to drop by $30 \%$ of the original value when it passes a stationary observer. If speed of sound in air is $350 \mathrm{~m} / \mathrm{s}$, then the speed of engine in $\mathrm{m} / \mathrm{s}$ is