Proportions Projectile Motion Problem

[gg5467]

Homework Statement

A projectile on level ground is launched with a certain speed v_i and has a downrange distance of Δx. What is Its new downrange distance if it is launched with a speed of 4v_i instead?

Homework Equations

Δx=vi*t (I think)

The Attempt at a Solution

Since it says speed in the question, I assumed that the projectile was launched horizontally, therefore only affecting the downrange distance by a factor of 4. I'm not sure if it is launched at an angle though, but I'm thinking it wasn't.[/B]

 

[brainpushups]

Although you are correct with your reasoning, my guess is that the intention of the question, although it was not specified, is that the projectile was launched at an angle. Have you discussed the range equation for projectile motion on flat ground? That would be the easiest way to answer the question, though you can reason out the answer without it.