A body of mass 1000 kg is moving horizontally with a velocity 6 m / s. If 200 kg extra mass is added, the final velocity (in m / s) is:

Solution

Physics sir · 3 steps

No horizontal force acts, so the momentum stays the same: share it over 1200 kg now.

1. What stays constant. The extra mass is added with no horizontal velocity of its own, and no external horizontal force acts. So the total horizontal momentum is the same before and after.

   m₁ v₁ = (m₁ + m₂) v₂

2. Put in numbers. Momentum before is 1000 × 6 = 6000 kg m s⁻¹. The new mass is 1000 + 200 = 1200 kg, so v₂ = 6000/1200 = 5 m s⁻¹.
3. So. The body slows down to 5 m s⁻¹, which is option (d).

The idea to keep. When mass is added or removed with no horizontal force, conserve momentum mv, not velocity. The same momentum carried by more mass means a smaller speed.

Answer from the NTA final answer key. Solution by PrepWiser.