A 9000 kg boxcar traveling at 17.0 m/s strikes a second boxcar at rest. The two stick together and move off with a speed of 6.5 m/s. What is the mass of the second car?

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To find the mass of the second boxcar, we can use the principle of conservation of momentum. According to this principle, the total momentum before the collision should be equal to the total momentum after the collision.

The momentum of an object can be calculated by multiplying its mass with its velocity. Let's assume the mass of the second boxcar is 'm2'.

Before the collision, the momentum of the first boxcar (m1) can be calculated as:
Momentum1 = mass1 * velocity1 = 9000 kg * 17.0 m/s

Since the second boxcar is at rest, the momentum of the second boxcar before the collision is zero (m2 * 0 = 0).

After the collision, the two boxcars stick together and move off with a speed of 6.5 m/s. The combined mass of the two boxcars can be calculated as the sum of their individual masses:
m1 + m2 = Total mass after collision
9000 kg + m2 = Total mass after collision

Using the conservation of momentum, we can set up the equation:
Momentum1 + Momentum2 = Total momentum after collision

(9000 kg * 17.0 m/s) + (m2 * 0) = (9000 kg + m2) * 6.5 m/s

Simplifying the equation:
153,000 kg*m/s = (9000 kg + m2) * 6.5 m/s

Now we can solve for the mass of the second boxcar (m2):

153,000 kg*m/s = 6.5 m/s * (9000 kg + m2)

153,000 kg*m = 6.5 * (9000 kg + m2)

Dividing both sides by 6.5 m/s:
23,538.46 kg = 9000 kg + m2

Subtracting 9000 kg from both sides:
m2 = 23,538.46 kg - 9000 kg
m2 = 14,538.46 kg

Therefore, the mass of the second boxcar is approximately 14,538.46 kg.