Work and motion strategies to a problem

[wallstreet]

Homework Statement

So the problem is getting at a basic understanding of the work energy theorem, and just asks for the work done by gravity at a ball's max height if the ball (with mass 0.25 kg) is thrown into the air with initial velocity of 30 m/s. using W=change in KE, the answer is -112.5 J

But if I use the formula vf^2 = vi^2 + 2ad, to determine d, I get d as approx. 46, and so W=294 x 46 = 13524 J ??

Homework Equations

The Attempt at a Solution

 

[JaWiB]

Where did 294 come from? And 46 what? (units!)

 

[wallstreet]

right, 46 meters. and the 294 (N) was the force calculated as mxa = 30 kg x 9.8 m/s2

 

[JaWiB]

You said the mass is .25 kg, not 30 kg

 

[wallstreet]

haha, right. not sure why my brain did that.