A 9600 kg boxcar traveling at 15 m/s strikes a stationary second car. The two stick together and move off with a speed of 7.0 m/s. What is the mass of the second car?
Whatever the law of conservation of momentum says it is.
Try applying it.
m1v1+m2v2=(m1+m2)v....(1) m1=9600kg m2=? v1=15m/s v2=0m/s v=7.0m/s. Find m2
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To find the mass of the second car, we can use the principle of conservation of momentum. The total momentum before the collision is equal to the total momentum after the collision.
The momentum of an object is given by the product of its mass and velocity. In this case, the momentum of the boxcar before the collision is given by the product of its mass (9600 kg) and its initial velocity (15 m/s), which is equal to (9600 kg)(15 m/s).
Since the second car is stationary before the collision, its initial velocity is 0 m/s, so its initial momentum is 0.
After the collision, the two cars stick together and move off with a speed of 7.0 m/s. The total momentum after the collision is given by the product of the combined mass of the two cars (9600 kg + mass of the second car) and the final velocity of 7.0 m/s.
According to the conservation of momentum, the total momentum before the collision is equal to the total momentum after the collision. This can be expressed as:
(9600 kg)(15 m/s) = (9600 kg + mass of the second car)(7.0 m/s)
To find the mass of the second car, we can rearrange the equation and solve for it.
First, let's simplify the equation by multiplying the velocities on both sides:
(144000 kg * m²/s²) = (67200 kg + 7.0 m/s * mass of the second car)
Next, we can rearrange the equation to isolate the mass of the second car:
67200 kg + 7.0 m/s * mass of the second car = 144000 kg * m²/s²
Subtracting 67200 kg from both sides:
7.0 m/s * mass of the second car = 144000 kg * m²/s² - 67200 kg
Dividing both sides by 7.0 m/s:
mass of the second car = (144000 kg * m²/s² - 67200 kg) / 7.0 m/s
Evaluating the right side of the equation will give us the mass of the second car.