Answer:
10. B
13. It's actually 30 seconds but 20 comes closest so B
14. B, any type of stretching is good before you perform any type of physical activity because it loosens up the muscles
15. D, all of the above
Explanation: 
I have done many sports in my life and am still very active, I grew to know most of these things through the years.
 
        
             
        
        
        
a. 46 m/s east
The jet here is moving with a uniform accelerated motion, so we can use the following suvat equation to find its velocity:

where
v is the velocity calculated at time t
u is the initial velocity
a is the acceleration
The jet in the problem has, taking east as positive direction:
u = +16 m/s  is the initial velocity
 is the acceleration
  is the acceleration
Substituting t = 10 s, we find the final velocity of the jet:
 
And since the result is positive, the direction is east.
b. 310 m
The displacement of the jet can be found using another suvat equation
 
where
s is the displacement
u is the initial velocity
a is the acceleration
t is the time
For the jet in this problem,
u = +16 m/s  is the initial velocity
 is the acceleration
  is the acceleration
t = 10 s is the time
Substituting into the equation,

 
        
             
        
        
        
You need to know the speed and direction of object
        
                    
             
        
        
        
Answer:
a cold air mass and a warm air mass merge together