Joe Student rolled a toy car down a ramp and measured how far it traveled along the floor.
He recorded the distance along with the original mass of the toy car. Then, he taped a
penny to the roof of the same toy car, measured its new mass, and rolled it down the same
ramp from the same starting position. Again, he measured the distance the toy car traveled
and recorded the data. He taped a 2
nd
penny to the toy car’s roof, measured its new mass,
and rolled it down the same ramp from the same starting position. And again, he measured
the distance the toy car traveled and recorded the data. Based on this data, he concluded
that the greater mass caused the car to roll a greater distance.
What was the error in the experiment?
How did he roll it? Did he give it a push or just let it roll by itself? If he just let it roll by itself, I don't detect any error, except that he might want to repeat the rolls many times, to make sure that the differences were not merely chance occurrences.
The error in this experiment is that Joe Student did not control all the variables properly. While he correctly manipulated the mass of the toy car by taping pennies to the roof, he did not keep the other variables constant.
To conduct a valid experiment, Joe should have kept the starting position of the toy car, the condition of the ramp, and the force applied to the car consistent throughout the experiment. By not controlling these variables, he introduced potential sources of bias or confounding that could have affected the distance traveled by the toy car.
For instance, if the starting position of the toy car was slightly different each time, it could have led to variations in the distance it traveled. Similarly, if the ramp was not maintained in the exact same condition, it might have influenced the car's motion and distance. Additionally, if Joe applied different forces to the car when rolling it, it could have affected the results.
To rectify the error, Joe should have ensured that the only variable he manipulated was the mass of the toy car, while keeping all other variables constant. By controlling the variables, he could have determined whether there is a causal relationship between mass and distance traveled.