A train travels 30m/s then breaks are suddenly applied producing a retarding force equal to 1/10 of the weight of the train runs on the distance through which the train runs on the track before coming to rest in.

  1. 👍 1
  2. 👎 0
  3. 👁 524
  1. F = - mg/10 = m a
    a = -g/10

    v = Vi + at = 30 - g t /10
    at stop v = 0
    t = 300/g = time to stop

    d = Vi t + (1/2)a t^2
    = 30(300/g) -(1/2)(g/10)(300^2/g^2)
    = 9000/g - (1/2)(9000/g)
    = 4500/g
    about 450 meters

    1. 👍 2
    2. 👎 1
  2. alternate way using energy
    (1/2) m Vi^2 = F d
    F = mg/10
    (1/2) m Vi^2 = m g d/10
    (30)^2 = g d/5
    900 *5 /g = d
    d = 4500/g

    1. 👍 0
    2. 👎 0

Respond to this Question

First Name

Your Response

Similar Questions

  1. physics

    A child is standing on a platform of a station. A train travelling at 30m/s takes 3.0 secs to pass the child.What is the length of the train. a)10m-this was my answer b)27m c)30m d)90m

    asked by sarah on November 9, 2014
  2. physic

    Superman must stop a 120km/h train in 150m to keep it from hitting a stalled car on the tracks.If the train's mass is 3.6x10^5kg,how much force must he exert?Compare to the weight of the train (give as%).How much force does the

    asked by noah on July 2, 2011
  3. Physics

    The Speed of train is reduced from 60km/h at the same time as it travels a distance of 450 m, If the retardation is uniform , find how much further it will travel (approx) before coming to rest? Answer is 30m but how? See my

    asked by Shahab Mirza on October 28, 2014
  4. physics

    A person pushes a 17.0 kg lawn mower at constant speed with a force of 74.0 N directed along the handle, which is at an angle of è = 48.0° to the horizontal (b) Calculate the horizontal retarding force on the mower (c) Calculate

    asked by kayla on February 2, 2012
  5. math

    IF the speed of train A is 10 mph slower than train B. Train A travels 220 miles in the same time it takes train B to travel 270. What is the speed of both trains.

    asked by nannypam on April 27, 2013
  1. physics

    A car that weighs 15,000 N is initially moving at 60km/hr when the brakes are applied. The car is brought to a stop in 30m. Assuming the force applied by the brakes is constant, determine the magnitude of the braking force.

    asked by Dale on June 11, 2011
  2. math

    Train #1 leaves san diego at 4pm. train #2 leaves san diego at 6pm.train #2 travels 42 mph faster than train #1. if train # 2 overtakes train #1 at 8pm, what is the speed of each train?

    asked by william on September 17, 2015
  3. Math

    Train A and train B leave station going in opposite directions. Train B leaves 1/2 later than train A. Train B travels 80km/h faster than Train A. In 2 hours the trains are 3200KMs apart. How fast is each train traveling.. thank

    asked by Lucas on October 16, 2007
  4. Algebra

    A train leaves a city heading west and travels at 50 miles per hour. Three hours later, a second train leaves from the same place and travels in the same direction at 65 miles per hour. How long will it take for the second train

    asked by Avery on June 1, 2010
  5. Physics

    Suppose that in the same Atwood setup another string is attached to the bottom of m1 and a constant force f is applied, retarding the upward motion of m1. If m1 = 5.30 kg and m2 = 10.60 kg, what value of f will reduce the

    asked by Rachel on October 24, 2009

You can view more similar questions or ask a new question.