1. The problem statement, all variables and given/known data If a particular spring is compressed 10 cm, it can launch a marble horizontally at 75 cm/s. How much must it be compressed to launch the marble horizontally at 150 cm/s? 2. Relevant equations 3. The attempt at a solution My guess is that the spring force needs to be doubled in order for the marble to reach double the height. Is this right? I feel like this is way too simple for my physics professor to put on an exam. I feel like there has to be something else like equations to try and solve this.