Velocity of Car after Unloading Gravel

In summary, the problem involves a 10,000 kg railroad car and a 4000 kg load of gravel being suddenly dropped in. Using the equation W = 1/2 mv(f)^2 - 1/2 mv(i)^2 and considering momentum to be conserved, the final speed of the car after the gravel is loaded is calculated to be 1.43 m/s. However, the answer key may be incorrect as it states the final speed to be 0.143 m/s.
  • #1
jeeves_17
10
0
1. A 10,000 kg railroad car is rolling at 2.00m/s when a 4000kg load of gravel is suddenly dropped in. What is the car’s speed just after the gravel is loaded?



Relevant Equations

W = 1/2 mv(f)^2 - 1/2 mv(i)^2

3. The Attempt at a Solution [/b]

W = 1/2 (14,000kg)v(f)^2 - 1/2(10,000)(2.0)^2


I'm lost:$
 
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  • #2
The most I can guess is that consider momentum to be conserved..you can find the initial momentum and then you can formulate the final and they should be equal
 
  • #3
Pi= mi*vi
= (10 000)(2.0)
= 20 000

Pi = Pf = 20 000

Pf = mf*vf
Vf = Pf/mf
= 20 000/14 000
= 1.42857
= 1.43 m/s


?
 
  • #4
Yes that would seem feasible as if it is heavier it would travel slower
 
  • #5
If you ignore friction and the initial velocity of the gravel then you can use conservation of momentum with ease.
2*10000 = V * (4000 + 10000)

I got 1.43m/s too. Explain the "?" Did you check it with the answer key and it's wrong or are you saying "is this right"? I'd say it's right.
 
  • #6
? meaning is it right...sorry for the confusion
 
  • #7
I did this same problem and got 1.43 m/s, but the books answer says .143 m/s. I was getting frustrated until I saw these posts. I guess the key is wrong.
 

What is the velocity of a car after unloading gravel?

The velocity of a car after unloading gravel depends on several factors, such as the weight of the car, the amount of gravel unloaded, and the surface on which the car is traveling. In general, the velocity will decrease as gravel is unloaded, due to the decrease in weight and potential decrease in traction.

How does the velocity of a car change as gravel is unloaded?

The velocity of a car will decrease as gravel is unloaded. This is due to the decrease in weight, which affects the car's acceleration and overall speed. Additionally, unloading gravel can potentially decrease the car's traction, which can also impact the velocity.

What is the relationship between the amount of gravel unloaded and the velocity of the car?

The relationship between the amount of gravel unloaded and the velocity of the car is inversely proportional. This means that as more gravel is unloaded, the velocity of the car will decrease. This is because unloading gravel decreases the weight of the car, which affects its acceleration and overall speed.

Does the surface on which the car is traveling affect its velocity after unloading gravel?

Yes, the surface on which the car is traveling can affect its velocity after unloading gravel. For example, if the car is unloading gravel on a rough or uneven surface, it may experience a greater decrease in velocity due to the potential decrease in traction. On a smooth surface, the impact on velocity may be less significant.

How can the velocity of a car after unloading gravel be measured?

The velocity of a car after unloading gravel can be measured using various methods, such as using a speedometer or a GPS device. Additionally, the velocity can also be calculated by measuring the distance traveled and the time it takes for the car to travel that distance. This can be done using equations such as velocity = distance/time or by plotting a velocity vs. time graph.

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