This problem is cited from http://zebu.uoregon.edu/~probs/mech/newt/2ndNewton1/2ndNewton1.html.

A train of mass 6.84x10^6kg is moving at a speed of 80 km/h. The brakes, which produce a net backward force of 1.93x10^6N, are applied for 25.0 seconds.
  1. What is the new speed of the train?
  2. How far has the train traveled in this time?

A physics object is represented as

class Object
{
factor m, f, a;
factor v, v0, t;
factor s;

f = m*a;
v = v0 + a*t;
a = v0^2/(2*s);
s = v0*t + a*t^2/2;
}

The questions can be answered by the query
_select v, d, a from object
where m=6.8410^6, v0=22.2, f=0-1.9310^6, t=25;_

The new speed of the train is around 87km/s, during this period, the train traveled around 466 meters.

Last edited May 24, 2009 at 3:02 PM by samhuang, version 1

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