Answer:
Explanation:
Given
For first case 
launch angle 
at highest point 


For second case 

at highest Point velocity is 

 
 
as there is no acceleration in x direction therefore horizontal velocity is same           
 
        
                    
             
        
        
        
Answer:
1/2 M V^2 = .1 M g H       where 10% of PE goes into KE
V^2 = .2 g H = .2 * 9.8 * (2100 - 1600) = 980 m^2 / s^2
V = 31.1 m/s       increase in speed during descent
1 km / hr = 1000 m / 3600 sec = .278 m/s
V = 31.1 m/s / (.278 m/s / km /hr)= 112 km/hr 
 
        
             
        
        
        
Average speed = (distance traveled) / (time to cover the distance)
                         =  (35 yards)  /  (3.8 seconds)
                         =     9.21 yards per second