The answer is static friction. This is the friction that involves objects that do not move.
        
                    
             
        
        
        
 Answer:
See below
Explanation:
Vertical position = 45 +  20 sin (30) t  - 4.9 t^2 
  when it hits ground this = 0
                0 = -4.9t^2 + 20 sin (30 ) t + 45 
                 0 = -4.9t^2 + 10 t +45 = 0     solve for t =4.22 sec
   max height is at  t= - b/2a = 10/9.8 =1.02
      use this value of 't' in the equation to calculate max height = 50.1 m
       it has  4.22 - 1.02 to free fall = 3.2 seconds free fall 
            v = at = 9.81 * 3.2 = 31.39 m/s VERTICAL
       it will <u>also</u> still have horizontal velocity =  20 cos 30 = 17.32 m/s 
         total velocity will be sqrt ( 31.39^2 + 17.32^2) = 35.85 m/s
Horizontal range = 20 cos 30  * t  =  20 *  cos 30  * 4.22 = 73.1 m 
 
        
             
        
        
        
The drop in physical activity is partly due to inaction during leisure time and sedentary behaviour on the job and at home. Likewise, an increase in the use of "passive" modes of transportation also contributes to insufficient physical activity.
 
        
             
        
        
        
I think its c or d but im not quite sure.....
        
             
        
        
        
Answer:
Gravity is the centripetal force when the moon orbits the earth.