Design

Example Research Questions

Here are some examples of good Research Questions, their Independent and Dependent Variables, and Controlled Variables:

Examples of Research Questions, Variables, and Controlled Variables 1. Research Question:  How does the speed of the belt of a Van de Graaff generator affect the maximum distance that a discharge spark can occur? Independent Variable:  Speed of the belt of the Van de Graaff generator (Note that speed can not be measured directly. The time for one revolution of the belt will be measured and the speed calculated.) Dependent Variable:  Maximum distance of discharge spark Controlled Variables:  Temperature of air in room Humidity of air in room Device used to induce spark 2. Research Question:  What is the relationship between the crater diameter and the mass of a ball that is dropped into sand from a fixed height? Independent Variable:  Mass of the ball that is dropped Dependent Variable: Diameter of the crater formed in the sand Important Controlled Variables:  Diameter of ball Surface of ball Spin of ball on impact Type of sand Dryness of sand How loose or compacted the sand is 3. Research Question: How does the color of light hitting a leaf affect the rate of photosynthesis in the leaf? Independent Variable:  Color of light hitting the leaf Dependent Variable:  Rate of photosynthesis in the leaf (Note that rate cannot be measured directly in this case.  The time for a leaf disc to rise in water will be measured, and 1/time will be taken as a relative measure of the rate of photosynthesis.) Important Controlled Variables:  Species of leaf Size of leaf disc Temperature of water in which leaf is submerged Intensity (brightness) of light hitting leaf 4. Research Question:  How does the temperature of a solution of 1.0 M ethanoic acid affect the acid equilibrium constant (Ka) of the ethanoic acid? Independent Variable:  Temperature of the ethanoic acid Dependent Variable:  Ka of the ethanoic acid (Note that Ka cannot be measured directly.  The pH will be measured and used to calculate the Ka) Important Controlled Variables:  Concentration of the ethanoic acid Device used to measure pH

 

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