A particle \(P\) of mass 2 kg is attached to one end of a light elastic string of natural length 1.2 m . The other end of the string is attached to a fixed point \(O\) on a rough horizontal plane. The coefficient of friction between \(P\) and the plane is \(\frac { 2 } { 5 }\). The particle is held at rest at a point \(B\) on the plane, where \(O B = 1.5 \mathrm {~m}\). When \(P\) is at \(B\), the tension in the string is 20 N . The particle is released from rest.
Find the speed of \(P\) when \(O P = 1.2 \mathrm {~m}\).