Question

practice - for each scenario below, identify the control, the independent variable, and the dependent variable. determine if the results of the test are trustworthy.

scenario 1: car safety experts are trying to determine if the type of tires affect how quickly a car can stop. they use 5 cars of the same make, model, and year. each car has a different type of tire.
the experimenters drive each car along a track until the car reaches 30 mph. they then engage the breaks to determine how long it takes the car to come to a complete stop, and record the distance traveled after the breaks were engaged.

control(s): ____
independent variable: ____
dependent variable: ____
is this test reliable? why or why not? ____

scenario 2: an experiment was performed to determine how the amount of coffee grounds could affect the taste of coffee. the experimenter used the same kind of coffee, the same type of coffee maker, the same amount and type of the same brewing time.

control(s): ____
independent variable: ____
dependent variable: ____
is this test reliable? why or why not? ____

Explanation:

Scenario 1

• Control(s): The factors kept constant to ensure a fair test. Here, cars of the same make, model, year, and initial speed (30 MPH) are controls.
• Independent Variable: The factor being changed. Here, it's the type of tires.
• Dependent Variable: The factor being measured. Here, it's the stopping distance (or time to stop).
• Reliability: The test is reliable. Because other variables (car make, model, year, speed) are controlled, so only tire type affects the result.

• Control(s): Factors kept constant. Here, coffee kind, coffee maker, amount/type of water, brewing time are controls.
• Independent Variable: The factor changed. Here, it's the amount of coffee grounds.
• Dependent Variable: The factor measured. Here, it's the taste of coffee.
• Reliability: The test is reliable. Because other variables (coffee, maker, water, time) are controlled, so only coffee grounds affect taste.

Answer:

• Control(s): Cars (same make, model, year), initial speed (30 MPH)
• Independent Variable: Type of tires
• Dependent Variable: Stopping distance (or time to stop)
• Is this test reliable? Why or why not? Yes, because other variables (car, speed) are controlled, so tire type is the only variable affecting the result.

Scenario 2