Dora rolled a marble down a ramp and recorded the potential energy and kinetic energy of the marble at different positions on the ramp, as shown in the table below. marble experiment height of marble from ground (meters) potential energy of marble (joules) kinetic energy of marble (joules) total energy of marble (joules) trial 1 1 2 4 6 trial 2 2 4 2 6 which is the constant variable in this experiment?