IGCSE 0625 Physics Formula
Chapter 1: General Physics Average Speed
s
=
d
t
s
=
d
t
s=(d)/(t) s = \frac{d}{t} s = d t where
s
s
s s s is speed,
d
d
d d d is distance, and
t
t
t t t is time.
Average Velocity
v
=
x
t
v
=
x
t
v=(x)/(t) v = \frac{x}{t} v = x t where
v
v
v v v is velocity,
x
x
x x x is displacement, and
t
t
t t t is time.
Acceleration
a
=
v
−
u
t
a
=
v
−
u
t
a=(v-u)/(t) a = \frac{v – u}{t} a = v − u t where
a
a
a a a is acceleration,
v
v
v v v is final velocity,
u
u
u u u is initial velocity, and
t
t
t t t is time.
Weight
W
=
m
g
W
=
m
g
W=mg W = mg W = m g where
W
W
W W W is weight,
m
m
m m m is mass, and
g
g
g g g is gravitational field strength (
9.8
m
/
s
2
9.8
m
/
s
2
9.8m//s^(2) 9.8 \, m/s^2 9.8 m / s 2 ).
Force
F
=
m
a
F
=
m
a
F=ma F = ma F = m a where
F
F
F F F is force,
m
m
m m m is mass, and
a
a
a a a is acceleration.
Density
ρ
=
m
V
ρ
=
m
V
rho=(m)/(V) \rho = \frac{m}{V} ρ = m V where
ρ
ρ
rho \rho ρ is density,
m
m
m m m is mass, and
V
V
V V V is volume.
Hooke’s Law
F
=
k
x
F
=
k
x
F=kx F = kx F = k x where
F
F
F F F is force,
k
k
k k k is the spring constant, and
x
x
x x x is extension.
Pressure
P
=
F
A
P
=
F
A
P=(F)/(A) P = \frac{F}{A} P = F A where
P
P
P P P is pressure,
F
F
F F F is force, and
A
A
A A A is area.
Fluid Pressure
P
=
ρ
g
h
P
=
ρ
g
h
P=rho gh P = \rho g h P = ρ g h where
P
P
P P P is pressure,
ρ
ρ
rho \rho ρ is density,
g
g
g g g is gravitational field strength, and
h
h
h h h is height.
Work Done
W
=
F
d
W
=
F
d
W=Fd W = Fd W = F d where
W
W
W W W is work,
F
F
F F F is force, and
d
d
d d d is distance moved.
Power
P
=
W
t
P
=
W
t
P=(W)/(t) P = \frac{W}{t} P = W t where
P
P
P P P is power,
W
W
W W W is work, and
t
t
t t t is time.
Kinetic Energy
K
E
=
1
2
m
v
2
K
E
=
1
2
m
v
2
KE=(1)/(2)mv^(2) KE = \frac{1}{2} m v^2 K E = 1 2 m v 2 where
K
E
K
E
KE KE K E is kinetic energy,
m
m
m m m is mass, and
v
v
v v v is velocity.
Gravitational Potential Energy
G
P
E
=
m
g
h
G
P
E
=
m
g
h
GPE=mgh GPE = mgh G P E = m g h where
G
P
E
G
P
E
GPE GPE G P E is gravitational potential energy,
m
m
m m m is mass,
g
g
g g g is gravitational field strength, and
h
h
h h h is height.
Efficiency
η
=
P
o
u
t
P
i
n
×
100
%
η
=
P
o
u
t
P
i
n
×
100
%
eta=(P_(out))/(P_(in))xx100% \eta = \frac{P_{out}}{P_{in}} \times 100\% η = P o u t P i n × 100 % where
η
η
eta \eta η is efficiency,
P
o
u
t
P
o
u
t
P_(out) P_{out} P o u t is useful power output, and
P
i
n
P
i
n
P_(in) P_{in} P i n is total power input.
Moment of a Force
M
=
F
d
M
=
F
d
M=Fd M = Fd M = F d where
M
M
M M M is the moment,
F
F
F F F is force, and
d
d
d d d is the perpendicular distance from the pivot.
Law of Moments
F
1
d
1
=
F
2
d
2
F
1
d
1
=
F
2
d
2
F_(1)d_(1)=F_(2)d_(2) F_1 d_1 = F_2 d_2 F 1 d 1 = F 2 d 2 where the sum of clockwise moments equals the sum of anticlockwise moments.
Momentum
p
=
m
v
p
=
m
v
p=mv p = mv p = m v where
p
p
p p p is momentum,
m
m
m m m is mass, and
v
v
v v v is velocity.
Impulse (Change in Momentum)
F
=
Δ
p
t
F
=
Δ
p
t
F=(Delta p)/(t) F = \frac{\Delta p}{t} F = Δ p t
Δ
p
=
m
v
−
m
u
Δ
p
=
m
v
−
m
u
Delta p=mv-mu \Delta p = mv – mu Δ p = m v − m u where
Δ
p
Δ
p
Delta p \Delta p Δ p is the change in momentum, and
F
F
F F F is force acting over time
t
t
t t t .
Chapter 2: Thermal Physics Boyle’s Law
P
1
V
1
=
P
2
V
2
P
1
V
1
=
P
2
V
2
P_(1)V_(1)=P_(2)V_(2) P_1 V_1 = P_2 V_2 P 1 V 1 = P 2 V 2 where
P
P
P P P is pressure and
V
V
V V V is volume.
Heat Energy
Q
=
m
c
θ
Q
=
m
c
θ
Q=mc theta Q = mc\theta Q = m c θ where
Q
Q
Q Q Q is heat energy,
m
m
m m m is mass,
c
c
c c c is specific heat capacity, and
θ
θ
theta \theta θ is the temperature change.
Celsius to Kelvin Conversion
C
=
K
−
273.15
C
=
K
−
273.15
C=K-273.15 C = K – 273.15 C = K − 273.15 Chapter 3: Waves Wave Speed
v
=
f
λ
v
=
f
λ
v=f lambda v = f\lambda v = f λ where
v
v
v v v is wave speed,
f
f
f f f is frequency, and
λ
λ
lambda \lambda λ is wavelength.
Frequency
F
=
1
T
F
=
1
T
F=(1)/(T) F = \frac{1}{T} F = 1 T where
F
F
F F F is frequency and
T
T
T T T is the period.
Refractive Index (Snell’s Law)
n
=
sin
i
sin
r
n
=
sin
i
sin
r
n=(sin i)/(sin r) n = \frac{\sin i}{\sin r} n = sin i sin r where
i
i
i i i is the angle of incidence, and
r
r
r r r is the angle of refraction.
Refractive Index (Speed of Light)
n
=
c
v
n
=
c
v
n=(c)/(v) n = \frac{c}{v} n = c v where
c
c
c c c is the speed of light in a vacuum and
v
v
v v v is the speed of light in the material.
Refractive Index (Critical Angle)
n
=
1
sin
c
n
=
1
sin
c
n=(1)/(sin c) n = \frac{1}{\sin c} n = 1 sin c where
c
c
c c c is the critical angle.
Chapter 4: Electricity and Magnetism Current
I
=
Q
t
I
=
Q
t
I=(Q)/(t) I = \frac{Q}{t} I = Q t where
I
I
I I I is current,
Q
Q
Q Q Q is charge, and
t
t
t t t is time.
Voltage
V
=
W
Q
V
=
W
Q
V=(W)/(Q) V = \frac{W}{Q} V = W Q where
V
V
V V V is voltage,
W
W
W W W is energy transferred, and
Q
Q
Q Q Q is charge.
Ohm’s Law
V
=
I
R
V
=
I
R
V=IR V = IR V = I R where
V
V
V V V is voltage,
I
I
I I I is current, and
R
R
R R R is resistance.
Power
P
=
I
V
P
=
I
V
P=IV P = IV P = I V
P
=
I
2
R
P
=
I
2
R
P=I^(2)R P = I^2 R P = I 2 R Energy Transferred
W
=
I
V
t
W
=
I
V
t
W=IVt W = IVt W = I V t
W
=
P
t
W
=
P
t
W=Pt W = Pt W = P t Resistors in Series
R
t
o
t
a
l
=
R
1
+
R
2
+
R
3
+
…
R
n
R
t
o
t
a
l
=
R
1
+
R
2
+
R
3
+
…
R
n
R_(total)=R_(1)+R_(2)+R_(3)+dotsR_(n) R_{total} = R_1 + R_2 + R_3 + \dots R_n R t o t a l = R 1 + R 2 + R 3 + … R n Resistors in Parallel
1
R
t
o
t
a
l
=
1
R
1
+
1
R
2
+
…
1
R
n
1
R
t
o
t
a
l
=
1
R
1
+
1
R
2
+
…
1
R
n
(1)/(R_(total))=(1)/(R_(1))+(1)/(R_(2))+dots(1)/(R_(n)) \frac{1}{R_{total}} = \frac{1}{R_1} + \frac{1}{R_2} + \dots \frac{1}{R_n} 1 R t o t a l = 1 R 1 + 1 R 2 + … 1 R n Resistance
R
=
ρ
l
A
R
=
ρ
l
A
R=(rho l)/(A) R = \frac{\rho l}{A} R = ρ l A Transformer Equations
V
s
V
p
=
N
s
N
p
V
s
V
p
=
N
s
N
p
(V_(s))/(V_(p))=(N_(s))/(N_(p)) \frac{V_s}{V_p} = \frac{N_s}{N_p} V s V p = N s N p
V
s
V
p
=
I
p
I
s
V
s
V
p
=
I
p
I
s
(V_(s))/(V_(p))=(I_(p))/(I_(s)) \frac{V_s}{V_p} = \frac{I_p}{I_s} V s V p = I p I s Chapter 5: Nuclear Physics Alpha Decay
92
238
U
→
90
234
T
h
+
2
4
H
e
92
238
U
→
90
234
T
h
+
2
4
H
e
_(92)^(238)U rarr_(90)^(234)Th+_(2)^(4)He {}^{238}_{92}U \rightarrow {}^{234}_{90}Th + {}^{4}_{2}He 92 238 U → 90 234 T h + 2 4 H e Beta Decay
90
234
T
h
→
91
234
P
a
+
−
1
0
e
90
234
T
h
→
91
234
P
a
+
−
1
0
e
_(90)^(234)Th rarr_(91)^(234)Pa+_(-1)^(0)e {}^{234}_{90}Th \rightarrow {}^{234}_{91}Pa + {}^{0}_{-1}e 90 234 T h → 91 234 P a + − 1 0 e Gamma Decay
Z
A
X
→
Z
A
Y
+
γ
Z
A
X
→
Z
A
Y
+
γ
_(Z)^(A)X rarr_(Z)^(A)Y+gamma {}^{A}_{Z}X \rightarrow {}^{A}_{Z}Y + \gamma Z A X → Z A Y + γ Chapter 6: Space Physics Orbital Speed
v
=
2
π
r
T
v
=
2
π
r
T
v=(2pi r)/(T) v = \frac{2\pi r}{T} v = 2 π r T where
v
v
v v v is orbital speed,
r
r
r r r is the radius of orbit, and
T
T
T T T is the orbital period.
Hubble’s Law
d
=
v
H
0
d
=
v
H
0
d=(v)/(H_(0)) d = \frac{v}{H_0} d = v H 0 where
d
d
d d d is the distance of a galaxy,
v
v
v v v is its speed away from us, and
H
0
H
0
H_(0) H_0 H 0 is the Hubble Constant (
2.2
×
10
−
18
s
−
1
2.2
×
10
−
18
s
−
1
2.2 xx10^(-18)s^(-1) 2.2 \times 10^{-18} s^{-1} 2.2 × 10 − 18 s − 1 ).
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