(answered) 
the simulation kept track of the variables and automatically recorded data on object displacement, velocity, and momentum. if the trials were run on a real track with real gliders, using stopwatches and meter sticks for measurement, how might the data compare? check all that apply.
this- there would be variables that would be hard to control, leading to less reliable data
- the data would be just as valid if it were recorded with a stopwatch.
this- meter sticks may lack precision or may be read incorrectly.
this-  real glider data may vary since real collisions may involve loss of energy.
this human error in recording or plotting the data could be a factor.
- controlling real glider velocities by hand would be just as accurate as simulation controls.