Proportions Projectile Motion Problem

1. Feb 19, 2015

gg5467

1. The problem statement, all variables and given/known data
A projectile on level ground is launched with a certain speed vi and has a downrange distance of Δx. What is Its new downrange distance if it is launched with a speed of 4vi instead?
2. Relevant equations
Δx=vi*t (I think)

3. 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.

2. Feb 19, 2015

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.