Answer:

Explanation:
consider the mass of each train car be m
m₁ = m₂ = m₃ = m
speed of the three identical train
u₁ = u₂ = u₃ = 1.8 m/s
m₄ = m             u₄ = 4.5 m/s
m₅ = m              u₅ = 0 (initial velocity )
final velocity 
v₁ = v₂ = v₃ = v₄ = v₅ = v
using conservation of momentum
m₁u₁ + m₂u₂ + m₃u₃ + m₄u₄ + m₅u₅ = m₁v₁ + m₂v₂ + m₃v₃ + m₄v₄ + m₅v₅
m (1.8 + 1.8 + 1.8 +4.5) = 5 m v


 
        
             
        
        
        
The total work is
         (mass of the elevator, kg) x (9.8 m/s²) x (9.0 m)           Joules .
        
             
        
        
        
Either no forces or a balanced group of forces
(not a group of "balanced forces"; there's no such thing)
        
             
        
        
        
Answer:
15
Explanation:
displacement = initial position - final position
 
        
             
        
        
        
Sorry I’m only in kindergarten is it 10kg must be supplied???