(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Find the speed at which Superman (mass=89.0 kg) must fly into a train (mass = 17755 kg) traveling at 85.0 km/hr to stop it.

Running into the train at that speed would severely damage both train and passengers. Calculate the minimum time Superman must take to stop the train, if the passengers experience an average horizontal force of 0.410 their own weight

How far does the train then travel while being slowed to a stop?

2. Relevant equations

p=mv

F=dp/dt

F=ma

J= p2-p1

J=F(t2-t1)

3. The attempt at a solution

I found the speed at which superman should fly by

m1v1=m2v2

17755*85.0=89.0*v2

v2=1.70×10^4 km/hr

for the minimum time this is what I do, but I got it wrong

since J=F(t2-t1)

and J=p(final)-p(initial)

then J=mv-mv

J=(89)(0)-(89)(1.70×10^4)

J=1513000

J=F(t2-t1)

1513000=(.41)(t)

t=3.68x10^6hr

then for the distance I couldn't calculate it because I had no idea what the time is

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Momentum to stop a train

**Physics Forums | Science Articles, Homework Help, Discussion**