A 100 g sphere is moving at a speed of 20 m/s and collides with another sphere of mass 50 g. If the second sphere was at rest prior to the collision and the first sphere comes at rest immediately after the collision, considering the collision to be elastic, the speed of the second sphere would be

The correct answer is Option D (40 m/s). This problem is solved using the Law of Conservation of Momentum, which states that in an isolated system, the total momentum before a collision is equal to the total momentum after the collision.

The formula is: m1u1 + m2u2 = m1v1 + m2v2

• Mass of first sphere (m1) = 100 g; Initial velocity (u1) = 20 m/s
• Mass of second sphere (m2) = 50 g; Initial velocity (u2) = 0 m/s (at rest)
• Final velocity of first sphere (v1) = 0 m/s (comes to rest)

Substituting the values: (100 × 20) + (50 × 0) = (100 × 0) + (50 × v2)
2000 + 0 = 0 + 50v2
2000 = 50v2
v2 = 2000 / 50 = 40 m/s.

Thus, the speed of the second sphere after the collision is 40 m/s.