energy - super compact set

what is work?

energy transfer from one store to another

mechanical vs electrical work?

mechanical = force moves object; electrical = current transfers energy

equation for work done?

W = F × d

kinetic energy & equation?

energy in moving objects; Ek = 0.5 × m × v²

elastic potential energy & equation?

energy in a stretched spring; Ee = 0.5 × k × e²

gravitational potential energy & equation?

energy due to height; Ep = m × g × h

thermal energy & specific heat capacity equation?

energy stored due to temperature; ΔE = m × c × Δθ

power & equations?

rate of energy transfer; P = E ÷ t or P = W ÷ t

law of conservation of energy?

energy can’t be created/destroyed, only transferred, stored, or dissipated

friction effects?

energy lost as thermal → less useful energy

reducing unwanted transfers?

reduce friction (lubricant) or remove obstacles; insulation for heat

thermal conductivity?

higher → faster heat transfer

increasing efficiency?

reduce energy wasted: lids on pans, electric kettle (heats water directly)

efficiency equation?

efficiency = useful ÷ total (energy or power)

fossil fuels: pros & cons?

pros = reliable, high energy, cheap, versatile; cons = CO₂ → climate change, non-renewable, pollutants

nuclear: pros & cons?

pros = no CO₂, reliable; cons = radioactive waste, expensive, dangerous if accident

renewables: pros & cons?

pros = never run out, no CO₂; cons = some unreliable (wind/solar), habitat impact (hydro/tidal), mostly electricity not transport, biofuels may affect food

UK energy plan?

renewables bulk, nuclear baseload, gas for peak demand

key steps (practical 1)?

measure mass of oil, starting temp, wrap in foam, supply energy with immersion heater & joulemeter, measure final temp, calculate c

sources of inaccuracy & fixes (practical 1)?

heat lost → better insulation; not all energy in oil → submerge heater; thermometer errors → use electronic; uneven heating → stir oil

testing materials (practical 2)?

small beaker inside large, 80 cm³ hot water, thermometer through lid, record temp every 3 min for 15 min, repeat with different insulators

variables (practical 2)?

independent = type of material; dependent = temp; controls = mass, starting temp, water volume

testing thickness (practical 2)?

wrap 2, 4, 6 layers newspaper, record temp; more layers → slower cooling → better insulation