Y9 Physics - Energy

Kinetic energy store (energy…objects)

energy in moving objects

Gravitational potential store (energy…objects)

energy in raised objects

Elastic potential store (energy…/…objects)

energy in stretched/squashed objects

Chemical energy store (energy in f.., f.., b..)

energy in fuels, food, batteries

Thermal energy store (ene…objects)

energy in hot objects

Magnetic store (energy in …)

energy in magnetic fields

Electrostatic store (energy in …)

energy in electric fields

Nuclear store (energy in…)

energy in atomic nuclei

Mechanical work (force c… m…)

force causing movement

Electrical work (cha… mov… i a c…)

charges moving in a circuit

Closed system

no net change in total energy

Dissipation (ene… spr… out into … stores)

energy spreading out into less useful stores

Kinetic energy equation

Ek = ½ mv² (kinetic energy = ½ x mass x speed²)

Effect of speed (…speed…kinetic energy)

doubling speed quadruples kinetic energy

Units (… for …, … for …, … for …) kinetic energy equation

joules for energy, kg for mass, m/s for speed

Elastic potential equation

Ee = ½ ke² (elastic potential energy = ½ x spring constant x extension²)

Spring constant (… of …(…/…))

stiffness of spring (N/m)

Extension (… in m…)

stretch in metres

Limit of proportionality (equation only …)

equation only valid before this point

GPE equation

g.p.e = mgw (gravitational potential energy = mass x gravitational field strength x weight)

gfs value (… …/… on Earth)

9.8 N/kg on Earth

Higher object (more …)

more GPE

Specific heat capacity (energy needed to … … by …)

energy needed to heat 1 kg by 1°C

High SHC (heats up … (eg …))

heats up slowly (e.g., water)

energy transfer equation

E=fs (energy transferred = force x distance)

Work done (… by a force)

energy transferred by a force

Units

joules for work, newtons for force, metres for distance

Power equation

Alternative power equation

(P = \frac{W}{t})

Power definition

(Total) energy transferred / time

Definition

rate of energy transfer

Units

watts (1 watt = 1 joule per second)

Efficiency equation

Efficiency as %

(useful ÷ total) × 100

Efficiency limit

cannot exceed 1 (100%)

Lubrication (decre… …)

Decreases friction

Insulation (… … loss)

reduces heat loss

Thicker walls (… cooling)

slower cooling

Low thermal conductivity (better …)

better insulation

High thermal conductivity

faster heat transfer

Battery store(… energy)

chemical energy

Battery transfer pathway (energy transferred …)

energy transferred electrically

Lamp transfer (…→ … + …)

electrical → light + thermal

Motor transfer

electrical → kinetic + thermal

Kettle transfer (…→…)

electrical → thermal

Speaker transfer(…→…+…

electrical → sound + thermal