What am I doing wrong in this basic Projectile Motion Problem?

[volleyballkay]

What am I doing wrong in this basic Projectile Motion Problem??

What I did in was use Delta X = Vxi + axt^2 & Delta Y= Vxi + ayt^2

then I plugged in the information but acceleration for x was 0m/s^2 and acceleration for y was -9.80m/s^2.

(ATTACHED AS FILE)

 

[cepheid]

Welcome to PF!

What I did in was use Delta X = Vxi + axt^2 & Delta Y= Vxi + ayt^2

then I plugged in the information but acceleration for x was 0m/s^2 and acceleration for y was -9.80m/s^2.

(ATTACHED AS FILE)

I don't know whether this is the only thing you are doing wrong, but it does seem like there are a few errors with your equations. It should be:

Δx = v_xit + (1/2)a_xt²

The parts you were missing are shown in bold.

 

[ehild]

What I did in was use Delta X = Vxi + axt^2 & Delta Y= Vxi + ayt^2

then I plugged in the information but acceleration for x was 0m/s^2 and acceleration for y was -9.80m/s^2.

The stone was thrown vertically upward. If Δx means horizontal displacement, the initial horizontal velocity is zero, the horizontal acceleration is zero, is Δx different from zero?
You need to work only with ΔY=V_yit + a_y/2* t^2. a_y = -9.8 m/s^2, that is correct. What is the initial velocity? What is ΔY when the stone strikes the ground?

ehild

 

[cepheid]

You meant Δx = v_xit + (1/2)a_xt², did you not?


ehild

Yeah I did. That was a very unfortunate typo.

 

[cepheid]

Edited