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solniwko [45]
3 years ago
6

A railroad car with a mass of 30,000 kg is moving at 2.0 m/s when it runs into an at-rest freight car with an equal mass. The ca

rs lock together. What is their final velocity?
Physics
1 answer:
11Alexandr11 [23.1K]3 years ago
4 0
The total momentum of the system is preserved through the collision.

Note that momentum is
P = m*v
where m = mass
v = velocity.

Initial momentum:
P1 = (30000 kg)*(2 m/s) = 60000 (kg-m)/s for the moving car
P2 = 0 for the starionary car.

Final momentum:
P3 = (30000 + 30000)*v = 60000v (kg-m)/s

Because momentum is preserved,
P3 = P1 + P2
60000v = 60000
v = 1 m/s
The final velocity is 1 m/s.

Answer: 1.0 m/s
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3 years ago
Sam is observing the velocity of a car at different times. After three hours, the velocity of the car is 53 km/h. After six hour
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For the answer to the question above, first find out the gradient. 

<span>m = rise/run </span>
<span>=(y2-y1)/(x2-x1) </span>

<span>the x's and y's are the points given: "After three hours, the velocity of the car is 53 km/h. After six hours, the velocity of the car is 62 km/h" </span>
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<span>(x2,y2) = (6,62) </span>

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<span>now we use a point-slope form to find the the standard form </span>
<span>y-y1 = m(x-x1) </span>
<span>where x1 and y1 are any set of point given </span>
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<span>y-53 = 3x - 9 </span>
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<span>y = 3x + 44 </span>

<span>y is the velocity of the car, x is the time.
</span>I hope this helps.
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