Question

Tara designed an experiment to determine how insulation affects the absorption of solar energy. She put a nylon sock over a Styrofoam cup and a cotton sock over a paper cup. She left a third glass cup uncovered. She filled the cups with 100 ml of room temperature water and then put them in the sun. She measured the temperature of each of the cups after 60 minutes. Which of the following statements accurately describes Tara's experimental design?

a) Water temperature cannot be used to indicate the amount of absorption of solar energy, so the design is flawed.
b) She used two variables - different materials and different types of cups, so the design was flawed.
c) Tara measured the absorption of solar energy, so the design is valid.
d) 60 minutes is not long enough to measure the absorption of solar energy, so the design is flawed.

Answer 1

Tara's experimental design to measure how insulation affects solar energy absorption is flawed since it uses different materials and types of cups as variables. The correct statement is (b), which acknowledges that the use of two variables (materials and cup types) prevents a clear understanding of the insulation factor alone.

Step-by-step explanation:

The experimental design to determine how insulation affects the absorption of solar energy is somewhat flawed because Tara used two variables - different materials for socks (nylon and cotton) and different types of cups (Styrofoam, paper, and glass). This introduces complexities in comparing the results, as the different cup materials may have varied thermal properties and capacities, which can influence the water temperature. Although water temperature can be used to indicate the amount of absorption of solar energy, when different container materials are involved, they may conduct or insulate differently, thereby affecting the rate of temperature change of the water they contain.

Therefore, statement (b) accurately describes Tara's experimental design - 'She used two variables - different materials and different types of cups, so the design was flawed.' This answer acknowledges the experimental error of including more than one independent variable, which prevents a clear determination of how insulation alone affects solar energy absorption.