Students will use a photogate to measure the launch velocity of a horizontal projectile. That velocity will be used to predict the projectile’s range, or horizontal displacement. The Marble Projectile Ramp is used to launch a marble horizontally from a table or desk. The included screws can be moved to provide up to four different starting points and velocities. You can use a photogate to measure the marble’s velocity as it exits the ramp and predict where it will land using projectile motion equations. In the second part of the lab, students will use energy conversion to predict the ball’s velocity at the end of the ramp. Students will find, however, that the marble’s real velocity is quite a bit slower than what they predict using this formula. In fact, a large part of the marble’s initial potential energy is converted into rolling energy.