physical science semester unit 1 1. in any experiment, what is the definition of an... a. ...independent variable? b. ...dependent variable? c. ...control variable? 2. for an experiment to be valid... a. ...does it need a hypothesis? b. ...how many things should be changed at a time? c. ...does it need to have control variables? why or why not?

Question

Accepted Answer

### Question 1
#### Part a
# Brief Explanations:
An independent variable in an experiment is the variable that the experimenter deliberately changes or manipulates. It is the cause in a cause - effect relationship being studied. For example, in an experiment testing how different amounts of fertilizer (independent variable) affect plant growth, the amount of fertilizer is what the researcher controls and changes.
# Answer:
An independent variable is the variable that the experimenter manipulates or changes in an experiment.

#### Part b
# Brief Explanations:
A dependent variable is the variable that is being measured or observed in an experiment. Its value depends on the changes made to the independent variable. Using the previous plant - growth example, the growth of the plant (height, number of leaves, etc.) is the dependent variable as it depends on the amount of fertilizer (independent variable).
# Answer:
A dependent variable is the variable that is measured or observed and whose value depends on the independent variable.

#### Part c
# Brief Explanations:
A control variable is a variable that is kept constant throughout an experiment. The purpose of a control variable is to ensure that any changes in the dependent variable can be attributed to the changes in the independent variable and not to other factors. For instance, in the plant - growth experiment, factors like the type of soil, amount of water, and amount of sunlight should be kept constant (control variables) so that we can be sure that changes in plant growth are due to the fertilizer (independent variable).
# Answer:
A control variable is a variable that is kept constant during an experiment to prevent it from influencing the relationship between the independent and dependent variables.

### Question 2
#### Part a
# Brief Explanations:
For an experiment to be valid, having a hypothesis is beneficial. A hypothesis is a testable prediction about the relationship between variables. It provides a clear direction for the experiment, stating what the researcher expects to happen. Without a hypothesis, the experiment may lack focus in terms of what is being investigated. So, in general, a valid experiment should have a hypothesis as it guides the experimental design and the interpretation of results.
# Answer:
Yes, an experiment should have a hypothesis. A hypothesis is a testable prediction that gives the experiment a clear focus and direction, helping to design the experiment and interpret the results.

#### Part b
# Brief Explanations:
For an experiment to be valid, only one thing (the independent variable) should be changed at a time. This is because if multiple variables are changed simultaneously, it becomes impossible to determine which variable is responsible for the changes observed in the dependent variable. By changing only the independent variable and keeping other variables (control variables) constant, we can establish a clear cause - effect relationship between the independent and dependent variables.
# Answer:
Only one thing (the independent variable) should be changed at a time. This is to determine the cause - effect relationship between the independent and dependent variables clearly, as changing multiple variables would make it hard to tell which one caused the change in the dependent variable.

#### Part c
# Brief Explanations:
An experiment needs to have control variables. Control variables are essential because they keep other factors constant, ensuring that any changes in the dependent variable are due to the independent variable and not other confounding factors. If there are no control variables, there could be multiple factors influencing the dependent variable, and we would not be able to accurately determine the effect of the independent variable. For example, in a plant - growth experiment, if we don't control the amount of water (a control variable), differences in water amount could affect plant growth, and we wouldn't know if the change in growth was due to fertilizer (independent variable) or water.
# Answer:
Yes, an experiment needs control variables. Control variables keep other factors constant, so that changes in the dependent variable can be attributed to the independent variable. Without them, confounding factors could influence the dependent variable, making it hard to determine the independent variable's effect.

Sovi.AI - AI Math Tutor

QUESTION IMAGE

Question

Explanation:

Question 1

Part a

Answer:

Part b