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3 years ago

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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?

1 answer:

Rufina [12.5K]3 years ago

3 0

Answer:

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

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3 years ago

2. A 55 kg woman has a momentum of 200 kg m/s. What is her velocity?

NeTakaya

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Explanation:

Velocity can be found using the following formula:

$v=\frac{p}{m}$

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$p= 200 \ kgm/s\\m=55 \ kg$

Substitute the values into the formula.

$v=\frac{200 \ kg m/s}{55 \ kg}$

Divide. Note that the kilograms, or kg, will cancel each other out.

$v=\frac{200 \ m/s}{55}$

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