Question

variable mass body with an initial mass of 5 kg is moving with a velocity of 5 m/s initially, after some time the velocity increases to 10 m/s, what is the new mass if the body is moving in the absence of any external force?​

Answer 1

Given info : variable mass body with an initial mass of 5 kg i smoving with a velocity of 5 m/s initially, after some time the velocity increases to 10 m/s.

To find : the new mass if the body is moving in the absence of any external force is ...

solution : here, external force acting on the body is zero, so the linear momentum of the system must be conserved.

i.e., initial linear momentum = final linear momentum

⇒ m₁v₁ = m₂v₂

here, m₁ = 5 kg , v₁ = 5 m/s , v₂ = 10 m/s

∴ 5 kg × 5 m/s = m₂ × 10 m/s

⇒ m₂ = 2.5 kg

therefore the mass of body will be 2.5 kg.