# Homework Help: Projectile Motion initial speed

1. Sep 11, 2011

### jsr219

For the initial speed of an ideal projectile, how many launch angles equal for the range of the projectile

-1

-2

-more than 2 but an infinite number of

-only one if the angle is 45 but other wise only 2

-an infinite number
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Sep 11, 2011

### Spinnor

3. Sep 11, 2011

### vkash

In 2 dimensional motion. that is -only one if the angle is 45 but other wise only 2 but if you thinking of 3d then there are infinite possible paths* as shown in images shown by Spinnor.

*I am not 100% sure in 3d case(I have read very little about it) because it depends on what's definition of range final position vector - initial position vector(if so then my answer is wrong) or minimum distance between final and initial position (if so then my answer is correct). can anybody please confirm me what's range definition.