Question

experimental variables (sc.7.n.2.1)
directions: read the following pages and answer the following questions
josiah wants to know how far a shot - putter from the track team can throw a shot. during the experiment, josiah measures independent and dependent variables. the drawings below show three different throwing angles from the experiment. assuming the shot - putter hurls the shot with the same force each time, identify the variable of the experiment.

1. what is the independent (tested) variable from this experiment?
2. what is the dependent variable from this experiment?
3. what are at least 2 constant variables from this experiment?
4. how can josiah show repetition in this experiment?
5. how can josiah show replication in this experiment?
6. the school physician performed an experiment to investigate the effects of aerobic exercise on high school freshmen. he examined 25 student volunteers, and then he had each student perform aerobic exercises, such as jogging, swimming, and bicycling. the doctor recorded the students pulse rates before each activity, during each activity, and after each activity.

independent variable:
dependent variable:

1. a student wants to test how the amount of fertilizer affects the growth of tomato plants. she sets up three pots with the same type of tomato plant. pot a receives no fertilizer, pot b receives one scoop of fertilizer each week, and pot c receives two scoops each week. all other conditions (amount of water, type of soil, amount of sunlight) are kept the same. after six weeks, she measures the height of the plants.

independent variable:
dependent variable:

Explanation:

Step1: Identify independent variable for shot - put experiment

The variable that is changed or tested is the throwing angle. So for the shot - put experiment, the independent variable is the throwing angle.

Step2: Identify dependent variable for shot - put experiment

The variable that is measured as a result of the change in the independent variable is the distance the shot is thrown. So the dependent variable is the distance the shot travels.

Step3: Identify constant variables for shot - put experiment

The force with which the shot - putter hurls the shot and the mass of the shot are constant. The same shot - putter and the same shot are used, and the force is kept the same.

Step4: Explain repetition in shot - put experiment

Repetition can be shown by having the shot - putter throw the shot multiple times at each angle. This allows for averaging of results and reducing error.

Step5: Explain replication in shot - put experiment

Replication can be done by having other shot - putters repeat the experiment with the same angles and force conditions.

Step6: Identify variables for aerobic exercise experiment

The independent variable is the type of aerobic exercise (jogging, swimming, bicycling). The dependent variable is the students' pulse rates.

Step7: Identify variables for fertilizer experiment

The independent variable is the amount of fertilizer (no fertilizer, one scoop, two scoops). The dependent variable is the height of the tomato plants.

Answer:

1. Throwing angle
2. Distance the shot travels
3. Force of throw, mass of the shot
4. Have the shot - putter throw multiple times at each angle
5. Have other shot - putters repeat the experiment
6. Independent Variable: Type of aerobic exercise; Dependent Variable: Students' pulse rates
7. Independent Variable: Amount of fertilizer; Dependent Variable: Height of tomato plants