Can someone answer all parts? ? extra points for this one!

     a) 
Acceleration of stone = 10 

Integrate: 
So velocity = 10t 

Integrate again: 
So distance from starting point = 5t^2 

Distance from ground = 450-5t^2 

b) 
450 - 5t^2 = 0 

9.48 seconds 

c) velocity = 10t 

Put the time into this to give: 

94.8 m/s 

d. 

Velocity = 10t + 5 

Integrate again: 

5t^2 + 5t 

Solve 
5t^2 + 5t = 450 

Gives 9 seconds