Question

A ball of mass 4 kg moving at 6 m/s collides with another ball of mass 6 kg moving at 4 m/s in the same direction. If the balls move together after the collision in the same direction, find their common velocity.

Answer 1

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Explanation:

Linear momentum is conserved

0.4×4+0.4×2=0.8×v

as shown in figure and B.

v=0.8

1.6+0.8 =3m/sKinetic energy before collision = 2

1 0.4(4) 2 + 2

1 0.4(2)

2=3.2+0.8=4J

Kinetic after collision = 21 0.8(v) 2 =0.8×3 2

=3.6

Loss of kinetic energy =4−3.6=0.4J

Answer 2

Explanation:

Linear momentum is conserved

0.4×4+0.4×2=0.8×v

as shown in figure and B.

v=0.8

1.6+0.8 =3m/sKinetic energy before collision = 2

1 0.4(4) 2 + 2

1 0.4(2)

2=3.2+0.8=4J

Kinetic after collision = 21 0.8(v) 2 =0.8×3 2

=3.6

Loss of kinetic energy =4−3.6=0.4J