Ask Question
24 September, 14:32

A freight car with a mass of 10 metric tons is rolling at 108 km/h along a level track when it collides with another freight car, which is initially at rest. If the speed of the cars after they couple together is 36 km/h, what is the mass of the second car?

+2
Answers (1)
  1. 24 September, 14:43
    0
    20 metric tons

    Explanation:

    Using the Principle of Conservation of Linear Momentum which states that the total momentum of a system is constant in any direction in which no external force acts.

    momentum before collision = momentum after collision

    mathematically expressed as

    m1u1 + m2u2 = m1v1+m2v2 = 0

    where:

    m1 = mass of rolling freight car = 10 metric tons = 10Mg

    1 ton = 1000kg = 1Mg

    u1 = initial velocity of freight car = 108km/h,

    m2 = mass of stationary freight car = ?, this the unknown we are finding

    u2 = initial velocity of

    m2 = 0, because it is at rest,

    v1 = final velocity of m1,

    v2 = final velocity of m2

    since they move together in the same direction they share a common final velocity as such

    v1=v2 = 36km/h

    substituting valves in expression give

    m1u1 + m2u2 = m1v1 + m2v2 = 0

    10Mgx 108km/hr + m2 x 0 = 10Mg x 36km/h + m2x36km/h

    1080 (Mg x km/hr) + 0 = 360 (Mg x Km/h) + 36m2 (km/h)

    1080 (Mgx km/hr) - 360 (Mg x km/h) = 36m2 (km/h)

    720 (Mg x km/h) = 36m2 (km/h)

    divide both side by 36 (km/h) gives

    m2 = 20Mg = 20 metric tons
Know the Answer?
Not Sure About the Answer?
Find an answer to your question 👍 “A freight car with a mass of 10 metric tons is rolling at 108 km/h along a level track when it collides with another freight car, which is ...” in 📗 Physics if the answers seem to be not correct or there’s no answer. Try a smart search to find answers to similar questions.
Search for Other Answers