An 18 000-kg freight car travelling 1.75 m/s[E] collides with a 27 000-kg freight car at rest. After the collision, the freight cars stick together. What is the velocity of the freight cars after the collision?

The velocity of the freight cars after collision is 0.7 m/s

Explanation:

Given;

mass of the first freight car, m₁ = 18000 kg

initial speed of the first freight car, u₁ = 1.75 m/s

mass of the second freight car, m₂ = 27000 kg

initial speed of the second freight car, u₂ = 0

Let the velocity of the freight cars after collision = v

Apply the principle of conservation of linear momentum;

m₁u₁ + m₂u₂ = v(m₁ + m₂)

18000(1.75) + 27000(0) = v(18000 + 27000)

31500 = 45000v

v = 31500 / 45000

v = 0.7 m/s

Therefore, the velocity of the freight cars after collision is 0.7 m/s

freezing

deposition

condensation

explanation;

melting also called fusion is the process where solid becomes liquid, sublimation is the process where solid becomes gaseous without first changing to liquid, deposition involves change from gaseous to solid state, freezing involves change from liquid to solid, boiling or evaporation involves change of liquid to gaseous state, while condensation is the change from gaseous state to liquid state.

endothermic reactions involves absorption of heat from the surroundings or the environment while exothermic reactions involves loss of heat energy to the surroundings.

in this case, sublimation, evaporation and melting are endothermic reactions (gain energy from the environment) while, freezing, deposition and condensation are exothermic (loss of energy to the surroundings) reactions.

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