# Projectile Motion - Equivalent javelin throw performed on the moon

## Homework Statement

Experts recommend a release angle of 35 degrees for javelin throwing, use this as the release angle. Determine what the length of the equivalent throw on the moon would be. Clearly communicate the procedure you followed, and fully justify your answer.

## The Attempt at a Solution

I'm not too sure about the information provided, as it hasn't given a velocity or a range of the projectile. But I guess a general rule for the conversion between a throw on Earth and its equivalent on the moon can still be determined?
I have read some solutions which say that the range will just be six times whatever it was on Earth, as the moon's gravity is approx. 1/6 of Earth's gravity.
I don't know whether it's just me overthinking, but that sounds way too simple!

## Answers and Replies

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gneill
Mentor

## Homework Statement

Experts recommend a release angle of 35 degrees for javelin throwing, use this as the release angle. Determine what the length of the equivalent throw on the moon would be. Clearly communicate the procedure you followed, and fully justify your answer.

## The Attempt at a Solution

I'm not too sure about the information provided, as it hasn't given a velocity or a range of the projectile. But I guess a general rule for the conversion between a throw on Earth and its equivalent on the moon can still be determined?
I have read some solutions which say that the range will just be six times whatever it was on Earth, as the moon's gravity is approx. 1/6 of Earth's gravity.
I don't know whether it's just me overthinking, but that sounds way too simple!
Hi rachel1234, Welcome to Physics Forums.

You should be able to derive an expression for the range of the projectile which will allow you to prove or disprove your conjecture. Assume that the javelin is launched with the same velocity V in both cases, and that the accelerations due to gravity are $g_e$ and $g_m$.

CWatters
Homework Helper
Gold Member
What gneil said.

Write the equation for the distance on earth. It will contain g. Replace g with 1/6 g.

Okay, I think I'm alright with that part now. Thank you!
Also, would I have to discuss the effects of drag, resistance, etc.? The javelin is already a rather streamlined design to reduce the effects of such forces.

haruspex