Carl knows that water moves through different kinds of soil at different rates. How easily water moves through a soil is known as permeability. Carl decides to compare the permeabilities of different soil types. To do this, Carl takes five identical flower pots with holes in the bottom and fills each one with different soil: rocky, gravely dirt from the side of the road potting soil from the store clay soil from a nearby creek sand from a store dirt from his own backyard Carl pours one liter of water into each pot and measures how much water flows out of the bottom in one minute. Which of the following variables should be kept constant during this experiment? (1 point) Responses A. the permeability of the soil in each pot A. the permeability of the soil in each pot B. the amount of water that goes into each pot B. the amount of water that goes into each pot C. the amount of water that comes out of each pot C. the amount of water that comes out of each pot D. the kind of soil in each pot D. the kind of soil in each pot Skip to navigation

Answer 1

In Carl's experiment, the variable that should be kept constant is:

B. the amount of water that goes into each pot

This is important to ensure that the only variable affecting the results is the type of soil, which will allow Carl to accurately compare the permeabilities of the different soil types. The other options (A, C, D) represent aspects of the experiment that are either the focus of the study or inherently different by design.

Answer 2

Arthur reads an article describing an experiment to test the effects of caffeine on the reaction time of humans—how long it took them to respond to a particular signal. In the experiment, the subjects' reaction times were measured, then they were divided into three groups. One group was given a high dose of caffeine. The second group was given a medium dose of caffeine. The third group was given a sugar pill that had no caffeine. After waiting 45 min for the caffeine to take effect, the reaction times were measured again. In the experiment Arthur read about, what was the outcome variable (dependent variable)? (1 point) Responses A. the amount of caffeine given to each person A. the amount of caffeine given to each person B. the amount of time the caffeine was given to take effect B. the amount of time the caffeine was given to take effect C. the type of signal each person responded to C. the type of signal each person responded to D. the change in reaction times for each person

Answer 3

In the experiment Arthur read about, the outcome variable (dependent variable) is:

D. the change in reaction times for each person

This is because the experiment is measuring how the different doses of caffeine affect the subjects' reaction times, making the change in reaction times the key outcome being assessed.

Answer 4

Eva is performing an experiment to determine which type of disinfectant kills the most bacteria. She has six plates of the same kind and amount of bacteria. She adds one of five different kinds of disinfectant to each plate and leaves one plate without any disinfectant as a control. What role does the test variable (independent variable) play in this experiment? (1 point) Responses A. The amount of bacteria killed determines the type of disinfectant used. A. The amount of bacteria killed determines the type of disinfectant used. B. The type of disinfectant used determines the type of bacteria used. B. The type of disinfectant used determines the type of bacteria used. C. The type of disinfectant determines the amount of bacteria killed. C. The type of disinfectant determines the amount of bacteria killed. D. The amount of bacteria killed determines the type of bacteria used. D. The amount of bacteria killed determines the type of bacteria used.

Answer 5

In Eva's experiment, the role of the test variable (independent variable) is:

C. The type of disinfectant determines the amount of bacteria killed.

This means that Eva is manipulating the type of disinfectant in order to see how it affects the outcome, which is the amount of bacteria killed.

Answer 6

The law of universal gravitation states that a gravitational force exists between all objects in the universe. This force is directly proportional to the masses of the two objects and inversely proportional to the distance between them. This principle is a law because (1 point) Responses A. it has been demonstrated to be without exception under certain stated conditions. A. it has been demonstrated to be without exception under certain stated conditions. B. it is contradictory to ideas proposed by other scientists. B. it is contradictory to ideas proposed by other scientists. C. it cannot be tested through a controlled scientific investigation. C. it cannot be tested through a controlled scientific investigation. D. it is subject to change as new technology and evidence emerges.

Answer 7

The principle is a law because:

A. it has been demonstrated to be without exception under certain stated conditions.

The law of universal gravitation has been consistently confirmed through experimentation and observation, making it a reliable scientific law.

Answer 8

30/30 thx!

Answer 9

You're very welcome! Congratulations on your perfect score! If you have any more questions or need further assistance, feel free to ask. Great job! 🎉