# Homework Help: Projectile Motion: Method of finding initial velocity in a lab

1. Nov 11, 2014

### Yme

1. The problem statement, all variables and given/known data
Determine the exit speed(initial velocity) of a marble exiting a launcher shot from a table.
The height of the table, distance of the x component and the time can be measured. t=? Vi=? Vix=?
2. Relevant equations
d= vi * t + 0.5*g*t^2
Vi^2=Vix^2*Viy*2
3. The attempt at a solution
I would be able to find the initial velocity for the marble if I launch it horizontally by setting Viy= 0 and finding the time for the y component and sub that into the x component.

tl:dr: My question is that is would the initial velocity for the marble launched horizontally be the same initial velocity if it was launched at an angle? (since perpendicular components are independent of eachother or does that not apply to this situation?)

2. Nov 12, 2014

### andrevdh

Not necessarily. It depends on the launching mechanism. If it is a spring for instance
we get that the stored energy in the spring is now used to increase both the kinetic
and potential energy of the marble, so it would have slightly smaller launching speed.