What is the momentum of an 80 car freight train traveling at 40km/h?

In summary, the momentum of an 80 car freight train traveling 40km/h with an average car weight of 100,000kg is 88,888,889 kgm/s. However, with external forces such as friction and drag, the train's speed would decrease if the engine was not pulling it.
  • #1
Tylemaker
4
0
I saw a freight train cruising by today and thought "The momentum of that thing must be mind-blowing". I only have high school physics and thus couldn't calculate the momentum including many external forces. Did some quick research and was wondering what the momentum of an 80 car freight train traveling 40km/h would be? The average car being approximately 110.2 tons or 100,000kg

I came up with:
p=mv
p= (100,000*80)*(11.11...)
p= 88,888,889 kgm/s
Thats a lot of momentum but with friction, drag etc what would it actually be?
 
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  • #2
Tylemaker said:
I saw a freight train cruising by today and thought "The momentum of that thing must be mind-blowing". I only have high school physics and thus couldn't calculate the momentum including many external forces. Did some quick research and was wondering what the momentum of an 80 car freight train traveling 40km/h would be? The average car being approximately 110.2 tons or 100,000kg

I came up with:
p=mv
p= (100,000*80)*(11.11...)
p= 88,888,889 kgm/s
Thats a lot of momentum but with friction, drag etc what would it actually be?

The momentum is exactly what you calculated it to be. Friction and drag would slow the train down if the engine weren't pulling... But as long as the train is moving at a constant speed the engine's pull is exactly balancing the friction and drag, thereby keeping the momentum constant.
 

1. What is momentum and how is it related to a freight train?

Momentum is a measure of the amount of motion an object has. In the case of a freight train, it is the product of its mass and velocity. This means that the heavier and faster the train is moving, the greater its momentum will be.

2. Why is momentum important for a freight train?

Momentum is important for a freight train because it helps it overcome resistance and maintain its speed. The momentum of the train allows it to travel long distances without constantly needing to be powered by the locomotives.

3. How is momentum calculated for a freight train?

Momentum is calculated by multiplying the mass of the train by its velocity. The mass of the train can be determined by adding up the masses of all the individual cars and the locomotives. The velocity can be measured using a speedometer or calculated using the distance traveled and the time it took.

4. Can momentum be changed for a freight train?

Yes, momentum can be changed for a freight train. It can be increased by applying more force to the train, such as by using a more powerful locomotive or by adding more cars. It can also be decreased by applying a braking force or by reducing the speed of the train.

5. What are the safety implications of momentum for a freight train?

The high momentum of a freight train can make it difficult to stop quickly, which is why train operators must carefully control the speed and apply brakes in advance. This is also why it is important for trains to follow designated tracks and signals to avoid collisions. Additionally, the high momentum of a freight train means that it can cause significant damage if it were to collide with another object.

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