Chapter 4 Flashcards
Define heat (4.1)
A form of energy that can be transferred through solids, liquids and gases.
Explain why you shouldn’t touch a water bottle during winter if you’re cold. (4.1)
Because heat travels from an area of high to low concentration. So therefore, the heat left on your hands (high concentration) would transfer to the bottle (low concentration).
Describe the particle model.
Solids: they are tightly compacted together and vibrate slowly, allowing it to hold its shape.
Liquids: compacted tightly but have more space between them, allowing them to move over each other and flow. Vibrate quicker than solid, holds shape of container.
Gases: Not bound together and travel in straight lines until they bump into each other. Particles spread out and take shape of container.
Explain what happens when you heat a substance.
When you heat a substance, the energy from the source transfers to the particles giving them kinetic energy so they begin to vibrate, and this turns into heat energy.
Why does expansion and contraction occur?
Expansion occurs when a substance is heated. They eventually gain so much energy that they break out of their state and become a liquid or gas. This explains why an ice cube melts into water and then evaporates into gas, vice versa for contraction.
Define temperature
Measure of the average kinetic energy of the particles of a substance.
What is ‘absolute zero’?
The point of temperature when there is no more heat and energy, the particles of the substance barely move at all. (-273 degrees celcius, 0 Kelvin)
How does a thermometer work?
Contains mixture of alcohol/mercury which expands/contracts and we can read the temperature based on the scale that corresponds. (mercury isn’t used much anymore due to health hazards - if it breaks it will evaporatre, intoxicating the air)
The ____ the temperature difference, the ____ the flow of heat.
When the temperature difference is greater, heat transfers faster. This explains why warm water freezes faster than cold water.
Define conduction and provide an example.
The method of heat transferring between two substances in contact in which heat is transferred by vibration of particles. Eg. Holding an ice block on your hands. Heat from hands (high temp.) transfer to ice (low temp.) Your hand becomes cold and the ice melts.
Contrast conductors and insulators.
Conductors are substances that transfer heat easily. Eg. Metal. Insulators are substances that are poor conductors. Eg. Gases can still hold heat but poorly conduct it.
Use your knowledge about insulation to give reasoning why only the top layer of a lake freezes.
Because the ice acts as an insulator for the water and life beneath.
Define convection and provide an example.
Transfer of heat in a liquid/gas due to less dense, warmer matter rising and denser, cooler matter falling. Because there is more space between particles, the density changes and hot air is less dense so it is pushed upwards by cooler air, creating a convection current. Eg. The room quickly gets hot when you turn on a heater with the help of convection currents.
Define radiation and provide an example.
The movement of heat in the form of electromagnetic waves. Eg. heat from the Sun that warms the Earth that travels through empty space to reach us. This infrared radiation is transmitted as invisible waves.
What is a possum skin cloak? How does it keep you warm?
A cloak made from possum skin made by the Aboriginals.
The hair on the possum skin traps heat to warm your body. This is because it has air pockets that trap air. Because air is a poor conductor, it keeps your heat from escaping.
Define sound
Form of energy produced when something vibrates, moving back and forth very quickly. It relies on vibrating particles so that it can pass through solids, liquids and gases.
Define sound waves
The movement of alternating compressions and rarefactions. These waves travel away from the source in a ripple motion.
Explain the areas of a sound wave.
At times, surrounding air particles are bunched together in regions or spread out. Bunched up areas in a sound wave are called compressions. Spread-out areas are called rarefactions.
In what way is sound transmitted through materials
Longitudinal waves.
TRUE OR FALSE? Sound travels faster through warm air than cool air
True. Warm air vibrates faster.