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.
(b) Find the change in kinetic energy.
(c) Find the final kinetic energy of the train if it started from rest.
(d) Find the final speed of the train if there was no friction.
-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