The speed of cart b is 6m/s while the total momentum of the systmen is 4200 kg m/s
<h3>Conservation of Linear Momentum</h3>
Given Data
- Mass of cart one M1  = 150kg
- Initial Velocity U1 = 8m/s
Mass of cart two M2  = 150kg
Velocity U2 = 6m/s
Applying the principle of conservation of linear momentum we have
M1U1+M2U2 = M1V1+ M2V2
a. what is the speed of cart b after collision
substituting our given data we have
150*8+ 150*6 = 150*5+150*V2
1200 + 900 = 1200+ 150V2
2100 - 1200 = 150V2
900 = 150V2
Divide both sides by 150
V2 = 900/150
V2 = 6m/s
b. what is the total momentum of the system before and after collision
Total Momentum in the system is 
Total momentum = Momentum before Impact+ Momentum after Impact
Total momentum = M1U1+M2U2 + M1V1+ M2V2
Total momentum = 1200 + 900 + 1200+ 900
Total momentum = 4200 kg m/s
Learn more about Conservation of Linear Momentum here:
brainly.com/question/7538238
 
        
             
        
        
        
The question is asking to describe and state and calculate what do the observer on the earth measure for the speed of the laser beam, and base on my research, the answer would be v = 1bc, I hope you are satisfied with my answer and feel free to ask for more 
        
                    
             
        
        
        
The formula for force exerted on/by a spring is 
F = k*e where k is the spring constant and x is the distance stretched from
unstrained position. This should allow you to find what you need.
 
Using F = k x e, 
where k is the spring constant, 
and e is the extension, 
The F is her weight = 45 X 0.80 
= 36 N
 
        
             
        
        
        
Answer: You can betterly understand what's around you and how it works
 
        
             
        
        
        
I’m pretty sure the answer would be D, sorry if it’s not correct!