Law of conservation of energy
Define the Law of Conservation of Energy
Energy cannot be created or destroyed, only transferred or transformed.
Name the type of heat transfer that occurs through direct contact between particles.
Conduction
What state of matter does sound travel fastest through: solids, liquids, or gases?
Solids
State the Law of Reflection in one sentence.
The angle of incidence equals the angle of reflection.
What happens to the components in a series circuit if one globe blows?
The whole circuit stops working because the path is broken.
A ball rolls down a hill. Identify the type of energy it starts with and the energy it gains as it moves.
It starts with gravitational potential energy and gains kinetic energy.
Why does a metal spoon get hot quickly when left in a pot of boiling water?
Heat travels through the spoon by conduction because metal particles are tightly packed and transfer energy easily.
Why does sound travel slower in air than in water?
Air particles are far apart, so vibrations take longer to pass between them.
Why do objects appear clearly when you look into a flat mirror?
Because light reflects off the mirror in a predictable way, sending the reflected rays directly to your eyes.
What is one advantage of using a parallel circuit in household lighting?
If one light goes out, the others stay on.
A toaster uses electrical energy. List one useful energy output and one wasted energy output.
Useful: heat.
Wasted: sound or extra heat to the surroundings.
Describe how convection currents form in boiling water.
Warm water rises because it becomes less dense, and cooler water sinks, creating a circulating current.
A student taps wood underwater. Who hears it first: someone underwater or someone on the pool deck?
The person underwater — sound travels faster in liquids than gases.
Compare reflection and refraction using a simple example for each
Reflection: light bouncing off a mirror.
Refraction: light bending when entering water.
What does an open circuit mean?
The pathway is broken, so current cannot flow.
Explain why no machine or appliance is ever 100% efficient.
Some input energy is always lost as waste (heat, sound, friction).
Explain why you can feel the Sun’s warmth even though space has no particles.
Heat travels from the Sun by radiation, which does not require particles.
Explain why sound cannot travel through outer space.
Space has no particles, and sound needs vibrating particles to move.
How does a periscope allow someone to see above an object?
Light hits the top mirror at an angle of incidence, reflects at the same angle, travels down the tube, then hits the bottom mirror at the same matching angle, and is reflected into the viewer's eyes.
Why do lights in a parallel circuit stay on even if one bulb burns out?
Each light has its own pathway, so current can still flow through the others.
A roller coaster reaches the bottom of the track with less energy than it started with. Explain where the “missing” energy went.
It was transformed into wasted heat and sound due to friction and air resistance.
Compare conduction, convection, and radiation using particle behaviour in each.
Conduction: particles collide in solids.
Convection: warm particles move and circulate in liquids/gases.
Radiation: heat travels as waves with no particles needed.
Why does sound travel so well through solids like metal rods?
Solid particles are tightly packed, so vibrations transfer quickly and efficiently.
Why does a pencil look bent when placed in a glass of water?
Light refracts (bends) because it changes speed when moving from water to air.
What is the formula to calculate current (I), voltage (V) and resistance (R)?
I=V/R
V=I×R
R=V/I