@elena

posted by .

thank you so much help with the problem. i have trouble solving part b of the problem you helped me with. it told me to give it as a percentage, I got 10% but it is wrong. can you please help me
Superman must stop a 190-km/h train in 180m to keep it from hitting a stalled car on the tracks.

part a)If the train's mass is 3.8×10^5kg , how much force must he exert (find the magnitude)?

part b)Compare to the weight of the train (give as %).

partc) How much force(in magnitude) does the train exert on Superman?



college physics - Elena, Sunday, April 29, 2012 at 5:09pm
(a) v=190 km/h =52.8 m/s,
a =v^2/2•s =(52.8)^2/2•180 = 7.74 m/s^2,
F = m•a = 3.8•10^5•7.74 = 2.94•10^6 N.
(b) Weight = mg = 3.8•10^5•9.8= 3.76•10^6 N.
(c) F12 = -F21 = >
F = 2.94•10^6 N.

  • @elena -

    nvm, i did it wrong. i already got the answer its 79% thanks

  • @elena -

    2.94•10^6 ....100%,
    3.76•10^6 ..... x %
    x=(3.76•10^6 /2.94•10^6)•100% =127.9%

  • @elena -

    3.76•10^6 ....100%,
    2.94•10^6 ..... x %
    x=(2.94•10^6 /3.76•10^6)•100% =78%
    It depends on what to take for the base for comparison

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. drbob222,math

    I've written back for the one i'm having trouble with of the previous in the previous message. Another question is that I want to verify doesn't this problem refer to solving. It is estimated that the Earth is losing 4000 species of …
  2. Algebra

    Once again, I have some confusing problems for math. If you know any answers, even if you only know one, please tell me the answer and walk me through it so I can actually understand how you get to it. Thanks! #1: A space craft travels …
  3. math

    I was given a problem 9x --- 15x I was told to simplify, I got 3y -- 5 I was told that was wrong. Is it and why?
  4. math

    What strategy did you use in solving this problem?
  5. Chemistry

    Need help solving this problem. A 0.188g sample of unknown metal, X (s), produced 71.4ml of hydrogen gas when reacted with HCl according to the equation: X(s)+2HCl(aq)--> XCl2(aq)+H2(g) The gas was collected over water at 23 degrees …
  6. Math 141

    I am having trouble with this problem. perform the indicated operations and simpily the result as much as possible a) (3x - 2) (x^2 + 2x - 4 ) the answer i got so far is 3x^3 + 4x^2 -16x + 8. Am i done or i have to conitnue to simplify?
  7. to ms.sue

    you know when i told you that i had trouble with percentage?
  8. statistics

    Help!!I have tried this several times and come up with wrong answer. WHAT PERCENTAGE OF A NORMAL DISTIBUTION IS GREATER THAN THE MEAN?
  9. math

    you have helped me so much, one more problem. Consider the following questions. (a) Chebychev's theorem guarantees that what percentage of a distribution will be included between x − 2.3s and x + 2.3s. (Give your answer correct …
  10. Math (Physics)

    Problem: An excited hydrogen atom could, in principle, have a radius of 2.50 mm . ________ Part A: What would be the value of n for a Bohr orbit of this size?

More Similar Questions