What is the initial projectile speed of the ball?

[kappcity06]

The pitcher in a slow-pitch softball game releases the ball at a point 3.0 ft above ground level. A stroboscopic plot of the position of the ball is shown in the figure below, where the readings are 0.25 s apart and the ball is released at t = 0. On the horizontal axis, x1 = 20 ft.


(a) What is the initial speed of the ball?
ft/s
(b) What is the speed of the ball at the instant it reaches its maximum height above ground level?
ft/s
(c) What is that maximum height?
ft


i tried to find part c first. since i know that time is equal to 1.25 seconds i used deltay=.5at^2
.5(32)(1.25)^2
25 feet
this did not work so I do not know what to do?
any one with any help. thaks

 

[hage567]

Why are you using t=1.25s in your calculation? That isn't the time it takes the ball to get to maximum height.

 

[Dorothy Weglend]

If you can answer (b), that will help you answer (c).

Dorothy

 

[Gib Z]

u=0 i think

 

[cristo]

u=0 i think

u can't be zero as the ball is pitched!

 

[kappcity06]

i am still not getting the answer. I also tried time as 1.25/2 but this is stil not right?

any one please

 

[hage567]

1.25/2 is the time to the maximum height. The equation you were using gives the change in height from where it started. Don't forget it was 3 ft above the ground when it was thrown. So if you want the total height above the ground you have to take that into account.

Does that help?