divide 2.49 by 5
2.49/5 = 0.498 rounded to nearest hundredth is 0.50 per pound
SSS - the side they're sharing is also congruent so if you just add in the other congruent sides you get SSS
Kinetic energy possessed by moving train is

.
And mass

.
The formula for kinetic energy is

.
Solve for velocity:


Now put in the data: