1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Dynamics - supertanker coasting to a stop

  1. Oct 17, 2013 #1
    Dynamics -- supertanker coasting to a stop

    1. Problem
    Assuming constant negative acceleration, how far does a supertanker of a mass of 250000 metric tons travel while coasting to a stop from an initial speed of 30 km/h in 21 min?
    What force is supplied by fluid friction of the water while the tanker is stopping?

    2. Relevant formulas
    S-S0 = (V+V0)t/2
    ma = sum (F)
    (1/2)at^2+v0t+S0=0
    v=at+v0

    3. Work I Did
    250k met ton = 250,000,000 kg
    30 km/h = 500 m/s
    21 min = 1260 s
    0 = 1260a + 500
    a = -500/1260
    (0+500)/2*1260 = 315 km (part a)
    ma = -F(friction)
    1000*(-50/126); Ff = 396.82 N (part b)

    a: 5.25 km
    b: 1.65*10^6 N
     
  2. jcsd
  3. Oct 17, 2013 #2

    CWatters

    User Avatar
    Science Advisor
    Homework Helper

    30km/h is not 500 m/s !
     
  4. Oct 18, 2013 #3
    Thanks!
    Using the same equations as I did in part a I got 5250 m -> 5.25 km; a = -5/756; v0 = 50/6.
    Part B I used 250,000,000 for the mass instead of 1000 kg and got the right answer.
    This is kind of embarrassing. I must've stared at the problem, confused, for quite a while.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Dynamics - supertanker coasting to a stop
  1. A Coasting Car (Replies: 4)

  2. Stopping Potential (Replies: 1)

Loading...