In the movie Spiderman 2 , there's a famous minute or two long scene where Spiderman stops a train . If the initial speed of a five car out of control subway train was around the top speed of the NYC subway (27 m/s), and Spiderman stopped the train in exactly one minute, then what is the magnitude of the force in Newtons that Spiderman exerted on the train as he stopped it?
Details and Assumptions
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
that force work in opposite direction. why not -90000N?
I like this step-by-step solution, Thanks....
Well, I did exactly the same but didn't actually know that train had 5 cars so my answer went wrong
dont know how to do f divides by t
Assuming
a
is constant (it is given),
Force
=
M
Δ
t
Δ
V
F = 5 × 4 0 0 0 0 kg × 6 0 sec 2 7 sec m
F = 9 0 0 0 0 N
After seeing the video : I think thats what Tobey's expressions were when he came to know that Andrew Garfield replaced him (just kidding)
I went the same way but I didn't add 5*...I don't know what the hell five-car is...
so..preparing for advance...(just saying)..nice answer
Log in to reply
Well, there is not much use of studying for 10 days. If I couldn't study it for 2 years, then surely I cant do it in such short amount of time. So, Im just studying bit by bit, and concentrating more on preparing my mind (calming my mind).
First notice that a standard New York City subway car full of terrified passengers has a mass of roughly 4 0 0 0 0 kg. And Spiderman stops five cars. So the total mass m Spiderman has to stop is equal to 4 0 0 0 0 × 5 kg or 2 0 0 0 0 0 kg.
Spiderman stops the car in exactly 1 minute or 6 0 seconds And he makes the car go from 2 7 m/s to 0 m/s in that time.
So, the magnitude of acceleration a caused on the car is equal to 6 0 2 7 m/s 2 .
Now use F = m a .
Plug everything in you're going to get F = 9 0 0 0 0 newtons.
I feel like I have solved this problem before.
To the staff, are you working on the Brilliant archive?
Haha I forgot there were 5 cars...
@Mursalin Habib Sue told me they are indeed working on the archive.
Yep according to Sue,the archive is currently under construction.
Since the train is a five car, the total mass of the train would be 40000 x 5 = 200000 kg. By the formula for momentum, p = mv, the momentum of the train is then 200000 x 27 = 5400000 Ns. Then, using the formula for impulse, Impulse = Fs, the force applied by Spiderman is 5400000/60 = 90000 N.
I just went with impulse here:
F ⋅ t = Δ p
F = m ⋅ a , and the mass is given as 4 × 1 0 4 k g . Δ p = p f − p 0 and since we know spidey stops the train, the final momentum is simply 0. We can easy calculate the initial momentum: p o = m v o = 4 × 1 0 4 k g ⋅ 2 7 m / s = 5 . 4 × 1 0 6 k g m / s , so the change in momentum is simply − 5 . 4 × 1 0 6 k g m / s .
Now we can calculate the acceleration using a = m ⋅ t Δ p . Plugging in numbers we arrive at: a = 2 . 0 × 1 0 5 k g ⋅ 6 0 s − 5 . 4 × 1 0 6 k g m / s = − 0 . 4 5 m / s 2
Now we can solve for the magnitude of the force required: ∥ F ∥ = m a = 2 . 0 × 1 0 5 k g ⋅ 0 . 4 5 m / s 2 = 9 × 1 0 4 N
Definitely simpler ways to get at the answer, but it seemed like a fun impulse problem. Hope that was useful. Cheers!
Problem Loading...
Note Loading...
Set Loading...
Going superHERO!
WEll as it was a constantly accelerated system I used v = u + a t equation .. where v = 0 , u = 2 7 m / s , t = 6 0 s e c o n d s
So a comes out to be 9 / 2 0 m / s 2 .
As the train is of 5 cars and each car of mass 4 0 0 0 0 kg , so the total mass is ⇒
2 0 0 0 0 0 kg .
Now .... F o r c e = M ⋅ a
⇒ F = 2 0 0 0 0 0 k g ⋅ 9 / 2 0 m / s 2
⇒ F = 9 0 0 0 0 N
So our SuperHERO has to have a force of 9 0 0 0 0 N to stop the train. Watch out the Vedio .