Posted by johnny on .
A horizontal spring with k=35N/m is compressed .085m and used to launch a .075kg marble. find the marble's launch speed. Repeat for a vertical launch.

Physics 180 
drwls,
Use conservation of energy.
Compressed spring potential energy = Launch kinetic energy
(1/2) k X^2 = (1/2) M Vo^2
X is the amount of spring compression.
Solve for Vo.
Vo = X*sqrt(k/M)
The launch speed will be nearly the same for a vertical or horizontal launch, but you will need to account for gravitation potential energy change, M g X, when the spring releases the marble in the vertical case.