physics
posted by dan on .
In the 1950s, an experimental train that had a mass of 3.30 104 kg was powered across level track by a jet engine that produced a thrust of 4.90 105 N for a distance of 600 m.
(a) Find the work done on the train.
1 J
(b) Find the change in kinetic energy.
2 J
(c) Find the final kinetic energy of the train if it started from rest.
3 J
(d) Find the final speed of the train if there was no friction.
4 m/s
how do you find KE?
whats the "work formula?"
calculating no friction? isnt that impossible?

1) Work = force • distance
Work = F2•3s = 4.9•105•600 =2.94•10^8 J.
2) work done = energy gained
Kinetic energy gained = 2.94•10^8 J It had 0 Ke to start, so this is its change in KE
3) This is also the final KE of the train
4) KE = m•v²/2
2.94•10^8 = 0.5•3.3•10^4• v²
V = sqrt (2.94•10^8/0.5•3.3•10^4) = 133.5 m/s