Find the total distance taken by the train.

  • Thread starter Thread starter Electgineer
  • Start date Start date
  • Tags Tags
    Train
AI Thread Summary
The discussion revolves around calculating the total distance traveled by a train that accelerates, moves at a constant speed, and then decelerates. The train accelerates at 6 m/s² for 20 seconds, reaches a constant speed, and then decelerates at 3 m/s² for another 20 seconds. Participants suggest using SUVAT equations to determine distances for each phase of motion, emphasizing the need to break the problem into three parts: acceleration, constant speed, and deceleration. The confusion arises from the deceleration phase, but it can be addressed by applying the appropriate equations for changing speeds. Overall, the calculation involves summing the distances from each segment of the train's journey.
Electgineer
Messages
11
Reaction score
0
[ A train starting from rest accelerate at the rate of 6m/s² for 20 seconds to attain a constant speed and it traveled for another 20 seconds and decelerate at the rate of 3m/s² for 20 seconds. Calculate the total distance (in kilometer) traveled by the train.
That's the question. I found it confusing when I was given the deceleration value.
 
Physics news on Phys.org
Electgineer said:
[ A train starting from rest accelerate at the rate of 6m/s² for 20 seconds to attain a constant speed and it traveled for another 20 seconds and decelerate at the rate of 3m/s² for 20 seconds. Calculate the total distance (in kilometer) traveled by the train.
That's the question. I found it confusing when I was given the deceleration value.
Why? What's confusing about the deceleration of the train?

The train starts from rest and accelerates to a constant speed. The train travels at this constant speed for a certain time interval. The train then slows down for another time period.

Apply the SUVAT equations for each type of motion and add up the distances traveled.
 
In both time intervals the speed of the train is changing.
In the first 20 s it is increasing.
In the next 20 s it is decreasing.
You can use the constant acceleration equations to calculate this.
How would you change the equations to calculate for the deceleration?
 
andrevdh said:
In both time intervals the speed of the train is changing.
In the first 20 s it is increasing.
In the next 20 s it is decreasing.
You can use the constant acceleration equations to calculate this.
How would you change the equations to calculate for the deceleration?
Try doing the problem in 3 parts. Part 1: What is the distance and velocity after accelerating at 6 m/s^2 for 20 seconds? Part 2: What is the distance after traveling at the constant velocity from Part 1 for an additional 20 seconds? Part 3: What is the additional distance and the final velocity after accelerating -3 m/s^2 for an additional 20 seconds?

Chet
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top