VERTICAL STONE THROW// That Painful Moment I Realized I Stopped Halfway

That Painful Moment I Realized I Stopped Halfway

Today, I was thinking of ways to turn my written explanation into a diagram.
So I snapped my solution and sent it to ChatGPT. The AI helped turn my text and diagram into something more real.

The original question didn’t state whether to take acceleration due to gravity(g) as 10 m/s^2 or 9.8 m/s^2, so I decided to try either way. I used 10 m/s^2.

I noticed something interesting: with both values, I got the vertical component of the final velocity as:
Square root of 800 which was approximately 28.28 m/s.

I chose that as my answer.

Then it hit me.

The vertical component and the horizontal component together make up the resultant velocity which can be gotten using pythagoras theory.

I said to myself:

Bro, you have not gotten to the final answer.

And as if to confirm, the genius who wrote the question seemed to whisper:

You have not reached your final destination.

That’s when it clicked.

The horizontal component Vx is constant throughout the motion. Gravity has no influence on it.

I had completely forgotten to include it.

Ouch. That was painful timing.

Yes — I had even written in my solution that energy is conserved:

Initial KE + initial PE = Final KE

1/2m u^2 + mgh = 1/2m v^2

That was correct. But I still stopped at the vertical component like it was the finish line.

The final answer was 30m/s...

Lesson learned

Always ask yourself:

Is this the final velocity, or just one part of it?

Combine your components.

Materials used

• University of Ibadan post UTME past question.

• Chat GTP for conversion and image generation.

• My solving skills.

• My judgment.

Thanks @stemsocial for giving me this privilege.