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:
