Heat Transfer
What is the transfer of heat through direct contact called?
Conduction
In an experiment, what do we call the factor that is changed on purpose?
Independent variable
What does it mean if an experiment is “reliable”?
It gives consistent results when repeated
What are molecules made of?
Atoms
Name the three main states of matter.
Solid, liquid, gas
Give an example of convection in everyday life.
Boiling water, warm air rising, etc.
What is the variable that is measured in an experiment?
Dependent variable
How can you increase the reliability of your results?
Repeat the experiment and average the results.
How do molecules move in a solid compared to a liquid?
Slower/less movement in solids, more in liquids
What state of matter has a definite shape and volume?
Solid
What type of heat transfer occurs from the Sun to Earth?
Radiation
What are variables that must be kept the same in an experiment?
Controlled variables (constants)
What is a control group, and why is it useful?
A group not exposed to the independent variable; used for comparison.
Draw or describe the arrangement of molecules in a gas.
Far apart, move freely
What must happen for a solid to become a liquid?
Heat must be added (melting).
Why do metal spoons get hot quickly when placed in hot soup?
Metals are good conductors of heat.
In an experiment testing how different materials affect ice melting, name the independent variable.
Type of material
Why should you write down your method in detail?
So others can repeat the experiment exactly.
What happens to molecules when heat energy is added?
They move faster.
Describe what happens to water molecules as it boils.
They move faster and spread apart into a gas.
Explain how a thermal flask keeps drinks hot or cold using the concept of heat transfer.
It reduces conduction, convection, and radiation.
Why is it important to have only one independent variable in a fair test?
To ensure results are due to that variable only.
If two groups get different results from the same experiment, what should they check for?
Errors, differences in method, or uncontrolled variables.
Explain how a model can show the difference between conduction and convection.
Conduction: vibration transfer; convection: movement of groups of molecules.
What is sublimation? Give an example.
Solid to gas without becoming liquid; dry ice.