${R_{max}} = \frac{{{u^2}}}{g}$ …..(i)
But $K.E.$ acquired by ball $= P.E.$ of spring gun
$ \Rightarrow \frac{1}{2}m{u^2} = \frac{1}{2}k{x^2}$
==> ${u^2} = \frac{{k{x^2}}}{m}$…..(ii)
From equation (i) and (ii)
${R_{max}} = \frac{{k{x^2}}}{{mg}} = \frac{{600 \times {{(5 \times {{10}^{ - 2}})}^2}}}{{15 \times {{10}^{ - 3}} \times 10}}=10\,m.$


$(A)$ Restoring torque in case $A =$ Restoring torque in case $B$
$(B)$ Restoring torque in case $A < $ Restoring torque in case $B$
$(C)$ Angular frequency for case $A > $ Angular frequency for case $B$.
$(D)$ Angular frequency for case $A < $ Angular frequency for case $B$.
