physics

if a train at 72kmphr is to be brought to rest in a distance of 200 m then its retardation is A 20m/s^2 b 10m/s^2 c 2m/s^2 d 1m/s^2

  1. 👍 0
  2. 👎 0
  3. 👁 199
asked by AYESHA
  1. 72/3.6 = 20 meters/second
    (helpful to remember 1000 meters /3600 seconds = 1/3.6)

    0 = 20 + a t
    t = -20/a

    x = Xi + Vi t + (1/2) a t^2
    200 = 0 + 20 t + .5 a t^2
    200 = 0 -400/a + .5 a (400/a^2)

    200 a = -400 + 200
    a = -1
    so d, retardation of 1 m/s^2
    ------------------------
    alternatively
    average speed during stop = 10 m/s^2
    200 = 10 t
    t = 20
    a = change in velocity/ time = -20/20 = -1

    1. 👍 0
    2. 👎 0
    posted by Damon

Respond to this Question

First Name

Your Response

Similar Questions

  1. mathematics

    A train takes 5mins to cover a distance of 3km between two stations P and Q. Starting from rest at P, it accelerates at a constant rate to a speed of 40km per hour and maintains this speed until it is uniformly brought to rest at

    asked by Michael on March 14, 2016
  2. Science

    a train takes 5 minutes to cover a distance of 3 km between two stations p and q . Starting from rest at p , it accelerate at a constant rate to a speed 40 km/h and maintain this speed untill it is brought to rest at q . If train

    asked by Anonymous on July 7, 2017
  3. Physics

    a train takes 5 minutes to cover a distance of 3 km between two stations p and q . Starting from rest at p , it accelerate at a constant rate to a speed 40 km/h and maintain this speed untill it is brought to rest at q . If train

    asked by Anver on July 7, 2017
  4. PHYSICS

    A train starts from rest and accelerates uniformly, until it has traveled 3 km and acquired a velocity of 20 m/s The train then moves at a constant velocity of 20 for 400 s. The train then slows down uniformly at 0.065 m/s2 until

    asked by CHLOE on May 25, 2010
  5. math

    A train traveling between two stations. The train starts from rest and accelerates uniformly for 150 seconds. It then travels at a constant speed for 300 seconds and finally decelerates uniformly for 200 seconds. Given that the

    asked by kd on September 9, 2019
  1. math

    Train traveling between two stations. The train starts from rest and accelerates uniformly for 150 seconds. It then travels at a constant speed for 300 seconds and finally decelerates uniformly for 200 seconds. Given that the

    asked by kd on December 21, 2019
  2. physics

    a train starts from rest and accelerates uniformly to achieve a velocity of 20m/sec in 10 sec.then train maintains this speed for next 200 sec.the breaks are then applied and train comes to rest in next 50 sec.calculate

    asked by parul on May 28, 2012
  3. physics

    a train starts from rest and accelerates uniformly to achieve a velocity of 20m/sec in 10 sec.then train maintains this speed for next 200 sec.the breaks are then applied and train comes to rest in next 50 sec.calculate

    asked by parul on May 30, 2012
  4. physics

    a train starts from rest and accelerates uniformly to achieve a velocity of 20m/sec in 10 sec.then train maintains this speed for next 200 sec.the breaks are then applied and train comes to rest in next 50 sec.calculate

    asked by PLZ HELP ME NOW... on May 30, 2012
  5. math

    The diagram below shows the speed time graph for a train travelling between two stations. The train starts from rest and accelerates uniformly for 150 seconds. It then travels at a constant speed for 300 seconds and finally

    asked by Anonymous on June 2, 2012

More Similar Questions