8. The correct answer is B. The period of a pendulum swing is directly proportional to the force of the push on the pendulum and inversely proportional to the length of the string. Theexperimentis not designed to measure the force of the pushmeaningthat thishypothesisis not appropriate for theexperiment.
9. The correct answer isgraph A. Data meant to showevidenceof acorrelationbetween twovariablesis best represented using ascatter plot. A properscatter plotshould have thedependent variable(in this case the period) on the y-axis.
10. The correct answer is B. Determining the correct response requiresinterpolationbased on the entiredata set. A validpredictionmust be between the periods for 40 cm and 25 cm and closer to the result for 25 cm.
11. The correct answer is C. The period will not be affected.Group #1’s data shows thatmassof bob does not impact the period of the pendulum.
12. The correct answer is B. The period of a pendulum’s swing is directly proportional to the length of the string.The relationship is a direct relationship and, because the period decreases by between 0.22 and 0.24 s with every 15 cm decrease in string length, a linear relationship is implied.
13. The correct answer is B. The correct answer is T=kL. The data suggests a direct linear relationship between period and string length. T=kL represents this relationship in slope-intercept form.
14. The correct answer is B. The air had alower opticaldensitythan the air below it.We are told by the passage that medium through which light travels faster has a lower optical density, and also that this air was "next to the ground".
15. The correct answer is C. Measuring the volume of the liquid instead of thetimespent pouring.Theexperimentis not about what is in the cup, it is related to how different liquids have different refractory properties. Using different liquids would be running the sameexperiment, but with differentvariables, and extra observers may increase experimentalaccuracy, but it does not relate to experimental method.
16. The correct answer is A. The direction of the light is perpendicular to the normal.Light either bends away from or towards the normal. If the angle to the normal is equal in both directions, no bending occurs.
17. The correct answer is C. 4.5 cmis the actual width of the bar. As stated in the passage, the index of refraction, and thus the magnification, of water is approximately 1.33. Multiply 4.5 cm by 1.33, and you get thesizeof the magnified image, 6 cm.
18. The correct answer is D. It cannot be determined because of the fact that rubbing alcohol has different refractive properties than water.Based on the data fromexperimentIII, we see that magnification and refraction are linked, and from table I,experimentI, we know that rubbing alcohol has a different refractive index than water.