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.
nvm, i did it wrong. i already got the answer its 79% thanks
2.94•10^6 ....100%,
3.76•10^6 ..... x %
x=(3.76•10^6 /2.94•10^6)•100% =127.9%
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
To solve part b of the problem, we need to compare the force Superman exerts on the train to the weight of the train.
The weight is calculated by multiplying the mass of the train (3.8×10^5 kg) by the acceleration due to gravity (9.8 m/s^2).
Weight = mass x acceleration due to gravity
Weight = 3.8×10^5 kg x 9.8 m/s^2
You can calculate the weight of the train by multiplying these two values together to get the answer in Newtons.
Weight = 3.8×10^5 kg x 9.8 m/s^2 = 3.76×10^6 N.
To express this as a percentage, we need to find what part of the force Superman exerts is compared to the weight of the train.
Percentage = (force exerted by Superman / weight of the train) x 100
To find the percentage, you can divide the force exerted by Superman (2.94×10^6 N) by the weight of the train (3.76×10^6 N), and then multiply by 100.
Percentage = (2.94×10^6 N / 3.76×10^6 N ) x 100
Simplifying this expression will give you the answer in percentage.