Two gliders collide on a frictionless air track that is aligned along the x axis. Glider A has an initial velocity of +4.0 m/s and a mass of mA = 0.20 kg. Glider B is initially at rest and has a mass mB. After they collide, A has a velocity of -1.0 m/s and B has a velocity of +2.0 m/s. Determine mB. Assume that It is an elastic collision.

As collision is elastic,thus we can use conservation of momentum equation

mA=0.2 kg

(vB)1=0 m/sas it is on rest before collision

(vA)1=4 m/s

(vA)2=-1 m/s

(vB)2=2 m/s

using equation

(mA*vA+mB*vB)1= (mA*vA+mB*vB)2

Where 1 and 2 represents before and after collision

(0.2*4)+(mB*0)=(0.2*-1)+(mB*2)

0.8=-0.2+(2mB)

mass of object B=mB=0.3 Kg

the answer is a)

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