# P1-P7

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## P1 Calculations

WD = Fx D           (J = N x d)

Work done = force x distance

Work done = movement AGAINST friction- Thermal energy is DISSIPATED.

GPE= m x g x h    (J = kg x 10N/kg x m)

Gravitational Potential Energy = mass x gravitational field strength x height

KE = 1/2 x m x v      (J = 1/2 x kg x m/s)

Kinetic energy = 1/2 x mass x velocity2

Efficiency = useful/total (x100)               Power = useful/total (x100)

Rate is dependent on WASTED energy

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## P2 Insulation Required Practical

1. MEASUREMENTS:

• Wrap material around the container
• Heat water (kettle) and pour a SET volume of water into container
• Measure INITIAL temperature and Measure TIME (5-10 minutes) using a stopclock, then measure END temperature and REPEAT for this material & different materials

2. CALCULATION:

• Calculate temperature difference (end - start temp.)

3. SAFETY:

• Beaker gets hot, don't touch

4. VALIDITY:

• Repeat & take average for each material and repeat with no layers (control)
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## P4 Electricity Pt.1

ELECTROSTATICALLY CHARGED:

• Transfer electrons due to friction
• Attraction between OPPOSITE charges

CHARGE EQUATIONS:

Q = I x t         (C = A x s)         Charge = current x time

E = Q x V      (J = C x V)          Energy = charge x potential difference (voltage)

(Complete circuits allow charge to flow)

V = I x R        (V = A x Ω)         Potential difference = current x resistance (Ohms)

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## P4 Electricity Pt.2

POWER EQUATIONS:

P = I x V         (W = A x V)         Power = current x potential difference

P = I2 x R        (W = A x Ω)        Power = current x resistance

E = P x t         (J = W x s)          Energy = power x time

MAINS ELECTRICITY:

• Mains - Frequency - 50 Hz
• Voltage - 230V
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## P6 Energy Pt.1

DENSITY:

M = ρ x V       (kg = kg/m3 x m3)       Mass = density x volume

l x w x h = volume (regular)       If you need to, change the unit FIRST

INTERNAL ENERGY:

total KE + total GPE

Inc. internal energy -> HEAT IT UP -> KE inc, first -> GPE inc. IF state changes

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## P6 Energy Pt.2

SPECIFIC LATENT HEAT:

E = m x L       (J = kg x J/kg)       Energy = mass x specific latent heat (SLH)

SPECIFIC HEAT CAPACITY:

E = m x C x ΔΘ     (J = kg x J/kg x oc)     Energy = mass x SHC  x temperature change

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Alpha                Beta                Gamma

α                       β                      γ

Helium        A single electron         Waves

ALPHA: Most ionising (CAN MUTATE CELLS), least penetrable

BETA: Not as ionising, more penetrable

GAMMA: Least ionising, most penetrable

HALF LIFE: Time taken to decrease radioactivity by a HALF

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