Posted by john on Sunday, April 29, 2012 at 5:50pm.
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 190km/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  john, Sunday, April 29, 2012 at 5:55pm
nvm, i did it wrong. i already got the answer its 79% thanks

@elena  Elena, Sunday, April 29, 2012 at 5:57pm
2.94•10^6 ....100%,
3.76•10^6 ..... x %
x=(3.76•10^6 /2.94•10^6)•100% =127.9%

@elena  Elena, Sunday, April 29, 2012 at 6:02pm
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
Answer This Question
Related Questions
 math  you have helped me so much, one more problem. Consider the following ...
 Math 141  I am having trouble with this problem. perform the indicated ...
 Chemistry  Need help solving this problem. A 0.188g sample of unknown metal, X...
 math  I was given a problem 9x  15x I was told to simplify, I got 3y  5 I ...
 to ms.sue  you know when i told you that i had trouble with percentage? well ...
 math  What strategy did you use in solving this problem? 22. Suppose that you ...
 drbob222,math  I've written back for the one i'm having trouble with of the ...
 statistics  Help!!I have tried this several times and come up with wrong answer...
 Algebra  Once again, I have some confusing problems for math. If you know any ...
 algebra1  could you walkthrough the steps to solving this problem because I am...
More Related Questions