A ball is thrown straight upward from the surface of the Moon. Is the maximum height it reaches less than, equal to, or greater than the maximum height reached by a ball thrown upward on Earth with the same initial speed? (Ignore air resistance in both cases.) Explain.

Question

theeric · Answer

Hi! What are your thoughts, at first?

anonymous · Answer

Hey! I am not entirely sure I am a little confused by the question but I believe that it may be equal to the maximum height

theeric · Answer

Okay! We'll start there. So, when you throw a ball up on Earth, why does it come down? Why does it stop, and then come down?

anonymous · Answer

Okay perfect! Wouldn't that be because of the gravity that would be pulling the ball back down?

theeric · Answer

Right! Now on the moon, there is less gravity, so less of a pull. If there is less of a pull, do you think the ball you throw will go farther, the same, or not as far up?

anonymous · Answer

Because there is less of a pull wouldn't that mean that it would not go as far up?

theeric · Answer

Well, there is less of a force to stop you from going upwards. So you would really go farther!

Another way to think about this is by going to the extreme. Think about there being $\sf no$ gravity. Then, what would a thrown ball do? There is nothing to pull it back. It will go on forever!
If there is gravity, it will go up, but eventually come down as it's upward velocity slows and heads downward.
If there is a lot of gravity, its velocity will be stopped and made to go down before it gets high up.

anonymous · Answer

Okay! that makes so much more sense now!!! so really the ball's maximum height it reaches will be greater than the maximum height reached by a ball thrown upward on Earth with the same initial speed because of your second explanation if there is gravity it will go up but eventually come down? :)

theeric · Answer

Right! And how long it takes to come down will depend on how hard gravity is pulling it down! :)

anonymous · Answer

yay! that is so exciting! I finally get it! :)

anonymous · Answer

thank you soo much!

theeric · Answer

You're very welcome! And congrats on understanding it! :)

anonymous · Answer

for sure its pretty great! :)

theeric · Answer

:D

anonymous · Answer

maybe you could help me with another one?! :)

theeric · Answer

Go ahead and post it! I'll take a look!

anonymous · Answer

on this feed or a new one?