Virtual Science Teachers

Bell Ringers: Energy

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Observe and Wonder

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States of Matter

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  1. Misconception: Solids are always hard and rigid.
    Some solids are soft or flexible (rubber, clay, gels). What defines a solid is a fixed shape and volume at given conditions, not hardness.
  2. Misconception: Liquids don’t have a fixed volume
    Liquids change shape to fit a container but keep (nearly) the same volume; they don’t expand to fill all space like gases.
  3. Misconception: Gases have no mass.
    Gases do have mass. A sealed, inflated ball weighs more than the same ball deflated, the difference is the mass of the gas.
  4. Misconception: During melting/boiling, temperature keeps rising.
    At the melting or boiling point, added energy goes into breaking intermolecular attractions, so temperature stays constant until the phase change is complete.
  5. Misconception: Boiling and melting points are single, unchanging numbers.
    They depend on pressure and composition. Water boils below 100 °C at high altitudes and above 100 °C in a pressure cooker; salt lowers water’s freezing point.
  6. Misconception: Evaporation and boiling are the same.
    Evaporation happens at the surface at any temperature; boiling happens throughout the liquid at the boiling point.
  7. Misconception: Dissolving is melting.
    When salt “disappears” in water, it doesn’t melt, it dissolves. The solid crystal lattice breaks into Na⁺ and Cl⁻ ions, each surrounded by water molecules; this state is called aqueous (aq), not solid and not “liquid salt.” Melting is a phase change of one substance; dissolving is a mixing process. If the water evaporates, the ions recombine and solid salt crystals form again.
  8. Misconception: Particles stop moving in solids.
    Particles in solids vibrate in place. Motion only approaches zero near absolute zero, which can’t be reached.
  9. Misconception: All matter is just solid, liquid, or gas.
    There are other states, including plasma (ionized gas in neon lights and the Sun) and Bose–Einstein condensates at ultra-low temperatures.
  10. Misconception: Plasma is just very hot gas.
    Plasma contains charged particles that conduct electricity and respond to magnetic fields, giving it behaviors different from neutral gases.
  11. Misconception: Glass is a liquid because old windows are thicker at the bottom
    Glass at room temperature is a solid (an amorphous solid). Old panes are uneven due to historical manufacturing, not flow.
  12. Misconception: You can’t compress liquids or solids.
    They are much less compressible than gases, but not perfectly incompressible; very high pressures can compress them slightly.
  13. Misconception: Sublimation doesn’t happen in everyday life.
    Dry ice goes directly from solid to gas, and snow/ice can slowly sublimate on very cold, dry days.
  14. Misconception: Humidity isn’t a gas.
    Water vapor is gaseous water mixed with air; it has mass and pressure and can condense when cooled.
  15. Misconception: A gas always fills the entire room instantly.
    Gases diffuse and mix over time; diffusion is faster at higher temperatures and with lighter molecules, but it isn’t instantaneous.

Heat Transfer

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  1. Misconception: Heat and temperature are the same.
    Temperature measures the average kinetic energy of particles. Thermal energy is the total kinetic energy in a sample. Heat is energy transferred from warmer to cooler because of a temperature difference.
  2. Misconception: Cold is transferred like heat
    There is no “cold flow.” Heat flows from the warmer object to the cooler one; we feel “cold” when our heat is leaving us.
  3. Misconception: Conduction is the only way heat moves.
    Heat also transfers by convection (moving fluids like air/water) and radiation (electromagnetic waves), not just conduction.
  4. Misconception: Metals heat up faster because they’re good conductors.
    Metals feel hot (or cold) quickly because they move heat fast to or from your hand; that sensation is about heat flow, not about the metal creating heat or reaching a higher temperature first. How fast an object’s temperature rises depends on both how easily heat moves through it (thermal conductivity) and how much energy it takes to warm it up (specific heat) plus its mass. A thin metal spoon handle gets hot quickly in soup because heat conducts along the spoon to your hand, while the soup itself warms slowly because water has a high specific heat and a large mass. In short, good conductors spread heat quickly, but heating rate is set by conductivity and heat capacity, not conductivity alone.
  5. Misconception: Insulators keep things warm by making heat.
    Insulators don’t make heat; they slow heat transfer, keeping hot things hot longer and cold things cold longer.
  6. Misconception: Thicker insulation always works better.
    More thickness helps, but material quality and installation matter. Diminishing returns mean twice the thickness isn’t always twice the performance.
  7. Misconception: Heat rises.
    Hot fluid rises because it’s less dense, creating convection currents. Heat itself can move in any direction by conduction or radiation.
  8. Misconception: Radiation needs air to travel.
    Radiation needs no medium. That’s how the Sun’s energy reaches Earth through the vacuum of space.

Thermal Conductors and Insulators

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  1. Misconception: All metals are good conductors.
    Conductivity varies. Copper and aluminum conduct well; metals like lead or bismuth conduct much less.
  2. Misconception: Insulators don’t conduct heat at all.
    Insulators slow heat transfer; over time some heat still gets through.
  3. Misconception: Thicker materials are always better insulators.
    Thickness helps only to a point. Material type and a good, gap-free fit matter more.
  4. Misconception: Conduction is the only way heat travels.
    Heat moves by conduction, convection (moving fluids), and radiation (infrared/light).
  5. Misconception: Cold is transferred like heat.
    Only heat flows, from warmer to cooler. “Cold” is just less heat or heat leaving.
  6. Misconception: Adding insulation makes something hotter.
    Insulation doesn’t make heat; it just slows heat loss (or gain).
  7. Misconception: Water is a good conductor of heat.
    Truth: Liquid water conducts poorly but moves heat well by convection when it circulates.

Conservation of Energy and Forms of Energy

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  1. Misconception: Kinetic energy depends only on speed.
    It depends on mass and the square of speed. Doubling speed makes KE about four times larger.
  2. Misconception: Stationary objects have no energy.
    Objects at rest can have potential energy (gravitational, elastic, chemical) and thermal energy.
  3. Misconception: Potential energy only means “height.”
    Height is one case (gravitational PE). Springs, stretched bands, charged objects, and chemical bonds also store potential energy.
  4. Misconception: Energy is used up or disappears.
    Energy is conserved. It changes form and often spreads out as thermal energy, which can be less useful, but it does not vanish.
  5. Misconception: Heavier objects always have more gravitational PE.
    Gravitational PE depends on mass and height. A lighter object higher up can have more PE than a heavier lower one.
  6. Misconception: Moving at a steady speed means no energy is involved.
    A moving object has kinetic energy. Keeping speed against friction or drag requires continuous energy input.
  7. Misconception: Batteries store electricity.
    Batteries store chemical potential energy that is converted to electrical energy in a circuit.
  8. Misconception: Electricity and electrical energy are the same thing.
    Electricity (current) is moving charges; electrical energy is the energy those charges carry and transfer.
  9. Misconception: Heat and temperature are the same.
    Temperature measures average particle motion; thermal energy is the total microscopic energy in the sample.
  10. Misconception: Sound can travel in space.
    Sound needs matter to vibrate. It cannot travel through a vacuum.
  11. Misconception: Light needs air to travel.
    Light (radiant energy) can travel through empty space; that is how sunlight reaches Earth.
  12. Misconception: Magnets provide free energy.
    Magnets can transfer energy, but they do not create it. Any work done comes from the system’s stored or supplied energy.
  13. Misconception: A compressed spring at rest has no energy.
    It stores elastic potential energy even when not moving.
  14. Misconception: Energy only comes in kinetic, potential, and thermal forms.
    Energy also appears as sound, light, electrical, chemical, nuclear, and magnetic, and these forms can convert between one another.
  15. Misconception: Hotter objects always have more thermal energy.
    A small, very hot object can have less total thermal energy than a large, cooler object; the amount of matter matters.