Answer:

Explanation:
Assuming that cars 4 and 5 have same mass so that the momentum
P=mv where m is mass and v is velocity hence
Momentum=0+2mv+3mv=5mv
The final mass is 2m+3m=5m
From aw of conservation of momentum
hence 
Therefore, the speed is 
Answer:

Explanation:
Given that,
The spring constant of spring 1, 
The motion of the object on spring 1 has twice the amplitude as the motion of the object on spring 2, 
As the magnitude of the maximum velocity is the same in each case, it means the maximum kinetic energy is same in each case. In other words, the total energy is same.




So, the spring constant of spring 2 is 920 N/m. Hence, this is the required solution.
Answer:
stress
Explanation:
Common causes of chronic insomnia include: Stress. Concerns about work, school, health, finances or family can keep your mind active at night, making it difficult to sleep. Stressful life events or trauma — such as the death or illness of a loved one, divorce, or a job loss — also may lead to insomnia.
I'm not sure, I think it's option A.
Let me know if I'm wrong!