The original velocity of the large train before the bump will be 3.999 cm/s.
Velocity can be defined as the rate of change distance with respect to time.
According to the law of conservation of momentum,
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
m₁ = mass of the first model electric train = 5.50 kg = 5500 g
u₁ = initial velocity of the first model train
m₂ = mass of the second model electric train = 550.0 g
u₂ = 0 m/s as it is at rest
v₁ = final velocity of the first model train after collision = 3.2727 cm/s
v₂ = final velocity of the second model train after collision = 7.2727 cm/s
By putting the values in the main equation, u₁ can be calculated,
5500*u₁ + 550*0 = 5500*3.2727 + 550*7.2727
5500*u₁ = 17999.85 + 3999.985
5500*u₁ = 21999.835
u₁ = 21999.835/5500
u₁ = 3.999 cm/s
The original velocity of the large train before the bump will be 3.999 cm/s.
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