Calculating Stopping Distance: Train vs. Cat on Track at 18m/s

In summary, a 25000kg train traveling at 18m/s on a track has to stop to avoid hitting a cat that wandered onto the track 45m ahead. The conductor slams on the brakes, which can provide 75000 Newtons of friction. Using the equation for change in kinetic energy, it is determined that the stopping distance is 54m. Since this is greater than the 45m distance to the cat, the conductor does not have enough time to stop and avoid hitting the cat.
  • #1
xbebegirlx
11
0
a 25000kg train travel down a track at 18m/s. a cat wander onto the track 45m ahead of train, causing the conductor to slam on the brakes. The train skids to a stop. If the brakes can provide 75,000 Newtons of friction, will the conductor have enough stopping distance to avoid hitting the cat?
 
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  • #2
Welcome to PF!

Hi xbebegirlx! Welcome to PF! :smile:
xbebegirlx said:
a 25000kg train travel down a track at 18m/s. a cat wander onto the track 45m ahead of train, causing the conductor to slam on the brakes. The train skids to a stop. If the brakes can provide 75,000 Newtons of friction, will the conductor have enough stopping distance to avoid hitting the cat?

Is this a lab experiment?

(I blame Schrödinger :rolleyes:)

What results did you get? :smile:

Show us what you've tried, and where you're stuck, and then we'll know how to help! :wink:

(Hint: you have the force and the distance, so the obvious thing to calculate would be the … ? :smile:)
 
  • #3
I have the Mass=25000kg
friction force = 75000n
time 18m/s
I don't know where the 45m fit in
I was confuse, to get stopping distance don't I need the coefficient of friction between the train and the rail? usually it giving but in this problem it not

I think I need to use this equation
change KE=1/2mvf^2-mvi^2
normal force:mg 25000kg(9.8m/s gravity) =245000n
friction force =coefficient * Normal force: 75000 =245000x; x =.306 this is my coefficient

vi^2=2*coefficient*gravity*Distance
18^2=2(.306)(9.8)D
324=5.998D
D=54.018m

so yes it have enough distance to avoid hitting the cat

Can someone help me check see if I got it right ?
 
  • #4
Hi xbebegirlx! :smile:
xbebegirlx said:
I don't know where the 45m fit in

It doesn't really! … you find D, and then right at the end you check whether D ≤ 45. :wink:
I was confuse, to get stopping distance don't I need the coefficient of friction between the train and the rail? usually it giving but in this problem it not

ah, you're not reading the question properly :redface:
…the brakes can provide 75,000 Newtons of friction
… the question doesn't bother to give you µ, it gives you µmg (= 75000N) all at once.

Try again. :smile:
 
  • #5
change KE =WF
ke=1/2mv
1/2*25000kg*18m/s^2 =75000x
d = 54M
no conduction don't have enough time to stoo

I hope this one right...because if not then I am stuck
 
  • #6
(what does WF stand for? :confused:)

I think you meant …
ke=1/2mv2 = work done
1/2*25000kg*182m/s^2 =75000xd
so d = 54m
no the conductor doesn't have enough time to stop :wink:

Yes, that's right. :smile:
 
  • #7
thanks
 

Related to Calculating Stopping Distance: Train vs. Cat on Track at 18m/s

What is stopping distance?

Stopping distance is the distance it takes for a vehicle to come to a complete stop after the brakes are applied. It includes both the distance traveled during the driver's reaction time and the distance traveled while the vehicle is decelerating.

What factors affect stopping distance?

The factors that affect stopping distance include the speed of the vehicle, the quality and condition of the brakes, the condition and type of the road surface, and the driver's reaction time.

How can I calculate stopping distance?

You can calculate stopping distance by using the formula: stopping distance = reaction distance + braking distance. Reaction distance is the distance traveled during the driver's reaction time, and braking distance is the distance traveled while the vehicle is decelerating. Reaction distance can be calculated by multiplying the speed of the vehicle in meters per second by the reaction time in seconds. Braking distance can be calculated by using the formula: (speed of the vehicle in meters per second)^2 / (2 x deceleration).

What is the average stopping distance for a car?

The average stopping distance for a car traveling at 60 mph is approximately 300 feet (91 meters). However, this can vary depending on the factors mentioned earlier.

How can I reduce my stopping distance?

To reduce your stopping distance, you can ensure that your brakes are in good condition and maintain a safe speed while driving. It is also important to stay alert and have a quick reaction time while driving. In addition, maintaining a safe distance from the vehicle in front of you can also help reduce your stopping distance.

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