A particle of mass 20gm) slides along the frictionless surface. When the particle reaches point B, its angular momentum (in kg m2/s) about O will be
Let the speed of particle be v when it reaches point B.
As there are no non-conservative forces acting on the particle, hence on applying law of conservation of mechanical energy, M.Ei=M.Ef ⇒KEi+PEi=KEf+PEf Taking PE=0 at the reference level, ⇒(12×0.02×52)+(0.02×10×10)=12×0.02×v2+0 ⇒v=15m/s....(1) Angular momentum about O L=mvr⊥ Since at B, r⊥=20m about O. ⇒L=0.02×15×20 ⇒L=6kg m2/s The angular momentum of the particle about point O when it reaches B is 6kg m2/s.