GCSE Physics

Topic P2

Motion

Radioactivity

Forces

Work,

Energy,

Momentum

Electricity

Mains

electricity

Speed = distance / time

Distance-time graphs

Gradient = velocity

Velocity - time graphs

Gradient = acceleration

Area under graph = distance travelled

acceleration = change in velocity

time taken for change

a = v - u

t

Force = mass x acceleration

F = m a

Springs

Hooke's Law:

stretching springs

Stopping distance =

thinking distance + braking distance

Be able to list 3 factors that affect

thinking distance and braking distance

and state how they affect it

(e.g.

alcohol

increases reaction time, which

increases thinking distance

)

Impact forces

depend on

rate of change of momentum

Momentum

(kg m/s)

=

mass

(kg)

x velocity

(m/s)

p = mv

Kinetic energy

= "half m v squared"

F t = m (v-u)

F = m (v-u)

t

So

increasing the duration (t)

of the collision

will

decrease the force

.

That's what airbags and crumple zones do.

"Work Done" is the energy needed to move an object.

W.D. = Force x distance

Grav. Potential Energy

= m g h

= Work Done lifting an object

= weight x height lifted

Throwing / Falling objects:

GPE at the top = KE at the bottom

Alpha

Beta

Gamma

Charge = +2

Mass = 4

Same as a He nucleus

Ionises strongly

Weak penetrating power

Charge = -1

Mass = tiny

Same as an electron

Ionises moderately

Moderate penetrating power

No charge

No mass

An electromagnetic wave

Ionises weakly

Strong penetrating power

Alpha

Beta

Gamma

Nuclear fission

= splitting large nuclei (e.g. U235)

to release energy

Nuclear fusion

= fusing small nuclei (e.g. H) together

to release energy. Lots of it.

Energy from

the nucleus

**Stars**

Line Spectra tell us

the elements in the star,

redshift of the lines tells us the star's speed

Life cycle of stars like our Sun

Life cycle of large stars

Link to "expanding universe" in Topic P1

Current (I) is the same all around a series circuit

Current is shared out in a parallel circuit

Amperes, ammeter

Voltage (V) is shared out in a series circuit

Voltage is the same across components in parallel

Also called "potential difference" (p.d.)

**Volts, voltmeter**

Ohm's Law

Resistance (Ohms) = voltage / current

R = V/I

Big resistance = bad conductor

I-V graphs for:

resistors

diodes

LDR's

Thermistors

Lamps

Gradient of I-V graph

tells you the resistance

(1/gradient)

Half life

:

the time it takes for half of the

unstable nuclei to decay

UK mains is 230V a.c. 50Hz

**Electrical safety**

Fuses

RCD's

Double insulation

**Earthing**

Power

(Watts)

= voltage x current

P = VI

Charge

(Coulombs)

= current x time Q = It

Energy = voltage x charge E = VQ

Higher [=H] &

Foundation

[=H]

[=H]

3-pin 13A

mains plugs

Balanced forces (resultant = 0)

means constant velocity

Terminal velocity

Rutherford's Experiment

= how we know atoms have a

small, +ve nucleus

http://www.darvill.clara.net/nucrad

**Explore**