Julian designs an experiment to see how well different liquids lubricate wooden surfaces. he sets up a number of identical wooden ramps and prepares to slide identical wooden blocks down them. he will time how long it takes each block to reach the end of the ramp. he covers one ramp with water, the second with motor oil, and the third with corn syrup. what can julian use as a control group for the experiment?

As a control group, Julian must use a wooden ramp that has not been covered with any type of liquid.

Explanation:

In an experiment, the control group is one that has not been subjected to the "object" being tested in the experiment. This group serves to compare the results of what is being tested.

In the question above, we can see that what is being tested is the liquids, in fact, what is being tested is the ability of these liquids to lubricate the wooden surfaces, for this reason, Julian, took 3 wooden ramps and covered each one with a different liquid, but julian needs a wooden ramp that will not be covered with anything to be the control group.