Paul's class investigated the effects of friction on the motion of a toy car. Using
ramps with different surfaces, students determined the amount of time, in seconds
(s), for the toy cars to reach the bottom of each ramp. All variables were controlled
except the tested variable (independent variable). Paul's group concluded that toy
cars on a sandpaper surface are fastest.
Which statement best evaluates the groups conclusion?
A. The results support the conclusion
B. More data need to be added to the conclusion
C. The conclusion is valid for the data recorded
D. The results fail to support the conclusion