1 A particle \(P\) of mass 1 kg is moving along a straight line against a resistive force of magnitude \(\frac { 10 \sqrt { \mathrm { v } } } { ( \mathrm { t } + 1 ) ^ { 2 } } \mathrm {~N}\), where \(\mathrm { vms } ^ { - 1 }\) is the speed of \(P\) at time \(t \mathrm {~s}\). When \(\mathrm { t } = 0 , \mathrm { v } = 25\). Find an expression for \(v\) in terms of \(t\).