a 6 kg mass collides with a body at rest .after collision they travel together with a velocity equal
to one-third of the velocity of the 6 kg mass. find the mass of the second body.
with calculation

12 kg

Explanation:

Momentum before collision = momentum after collision

m₁ u₁ + m₂ u₂ = m₁ v₁ + m₂ v₂

After the collision, they have the same velocity, so v₁ = v₂ = v:

m₁ u₁ + m₂ u₂ = m₁ v + m₂ v

m₁ u₁ + m₂ u₂ = (m₁ + m₂) v

We know that m₁ = 6 kg, u₂ = 0 m/s, and v = u₁ / 3.

(6 kg) u₁ + m₂ (0 m/s) = (6 kg + m₂) (u₁ / 3)

(6 kg) u₁ = (6 kg + m₂) (u₁ / 3)

6 kg = (6 kg + m₂) (1/3)

18 kg = 6 kg + m₂

m₂ = 12 kg

the working equation for the angular size is the product of the physical size and 360 degrees divided by the product of two pi and distance from earth. the minimum size would be 0.559 degrees while the maximum size would be 0.49 degrees. 

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach