FORCES AND ENERGY
Use density to explain why a wooden block floats on water but a small steel ball sinks.
Wood floats because its average density is less than water; steel has greater density than water so it sinks.
Describe how amplitude and loudness relate.
Loudness ∝ amplitude.
In a simple parallel circuit with two identical bulbs, describe how the current from the battery divides between the two branches.
In a parallel circuit, the total current splits; each branch gets a portion depending on its resistance. Identical bulbs get equal current.
Explain briefly how convection currents in the mantle drive tectonic plate movement.
Hotter rock rises and cooler rock sinks in the mantle; this convective flow drags plates at the surface.
Describe the difference between heat and temperature.
Heat is the transfer of thermal energy; temperature measures the average kinetic energy of particles in an object.
Explain how frequency relates to pitch. If two tuning forks vibrate at different frequencies, which one has the higher pitch?
Higher frequency → higher pitch; the tuning fork with higher vibration frequency has a higher pitch.
Describe how you would measure the current through and the voltage across a single lamp in a series circuit using an ammeter and a voltmeter.
Ammeter in series with the lamp; voltmeter in parallel across the lamp. Ammeter measures current through component; voltmeter measures potential difference across it.
List four pieces of evidence that support the theory of plate tectonics (use the jigsaw coastlines, volcano and earthquake locations, fossils, and magnetic alignment as examples).
Jigsaw fit of continents (e.g., South America and Africa), matching fossils across oceans, belts of volcanoes/earthquakes along plate boundaries, and magnetic striping in ocean crust showing reversals.
State the law of conservation of energy in your own words and give one everyday example.
Energy cannot be created or destroyed—only transformed (e.g., chemical energy in food → kinetic energy when you run).
Two sound waves meet and their peaks line up. What happens to the resulting sound?
Peaks aligning → constructive interference (reinforcement) producing larger amplitude (louder sound).
Calculate the resistance of a resistor if the measured voltage across it is 12 VOLTS and the current through it is 3 Amperes.
4 Ohms
Outline the main steps in the carbon cycle limited to photosynthesis, respiration, feeding, decomposition and combustion.
Photosynthesis: plants take in CO2 → glucose; Respiration: organisms break down glucose releasing CO2; Feeding: transfer of carbon through food chains; Decomposition: returns carbon to soil/atmosphere; Combustion: burning fossil fuels/biomass releases CO2.
Explain why thermal energy always flows from a hotter object to a colder one; name this process.
Heat flows from hot to cold because heat spontaneously transfers toward thermal equilibrium; called heat dissipation or heat transfer.
Describe one practical example of sound cancellation or reinforcement.
Out-of-phase waves can undergo destructive interference partially or fully (active noise-cancelling headphones as an application).
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Draw a circuit diagram (use conventional symbols) that includes: one cell, one switch, one variable resistor, one lamp, one ammeter (in series) and one voltmeter (in parallel with the lamp). Briefly explain where each instrument is placed.
Voltmeters across the lamp, ammeter in series with the circuit; switch breaks the series path; variable resistor in series to adjust current
Describe two historical or predicted impacts of climate change on sea level and extreme weather, and explain why these occur.
Sea level rise from thermal expansion and melting ice; increased flooding, droughts and stronger storms due to altered precipitation patterns and warmer atmosphere holding more moisture.
Describe the three modes of thermal transfer—conduction, convection, and radiation—and give one real-world example of each.
Conduction: transfer via particle collisions (metal spoon in hot soup). Convection: bulk movement of fluid carrying heat (boiling water currents). Radiation: electromagnetic waves transfer heat without medium (sun warming skin).
Given two sine waves of equal amplitude: one at f and one at 2f, describe qualitatively how their superposition would affect perceived sound (consider beats or timbre).
Superposition of f and 2f produces a more complex waveform; perceived timbre changes rather than simple beats (beats require close frequencies).
If you add more identical cells in series to a circuit powering a lamp, describe the effect on the lamp’s brightness and explain using voltage and current concepts.
More cells in series increase total voltage, increasing current (if resistance roughly constant) and making lamp brighter (until lamp limits).
Explain the collision theory for the Moon’s formation and describe one piece of evidence that supports this theory.
Giant impact hypothesis: Moon formed from debris after a Mars-sized body collided with early Earth; supporting evidence includes Moon’s composition similar to Earth’s mantle and angular momentum of Earth–Moon system.