The answer is 30 ... same as the Atomic number.
Answer:
I believe it's frictional force
The components of the ball's position
at time
are

The ball stops 18.0 m from where it began, so that

From the second equation, we can show that the ball travels for about
seconds, which means it was initially thrown with a horizontal velocity of

I don’t see any answer choice but the best way is asking questions about the natural phenomenon, making hypothesis, and predicting the consequences in the hypothesis.