A particle of mass 0.1 kg is subjected to a force which varies with distance as shown in fig. If it starts its journey from rest at x=0, its velocity at x=12 m is

Area between curve and displacement axis = 12×(12+4)×10 = 80 JIn this time body acquire kinetic energy = 12mv2by the law of conservation of energy  12mv2=80J⇒12×0.1×v2=80  ⇒ v2 = 1600 ⇒ v = 40 m/s