Flashcards in Equations Deck (41)
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1
Current
Change in Q / change in t
2
V=
W / Q
3
resistance
V / I
4
Ohms law
I is directly proportional to V under constant physical conditions
5
Resistivity , ρ
RA / L
(Cross sectional area )
6
Resistors in series, total R
R1 + R2 ....
7
Resistors in parallel , total R
1/R1 + 1/R2 ...
8
E , energy
IVt
9
P , power (3 parts )
IV = I^2R = V^2 / R
10
ε , emf (with energy)
E /Q
11
ε, emf (with resistance)
I (R + r)
12
V, velocity
Change in s (displacement ) / change in t
13
a acceleration
Change in v / change in t
14
What condition do the suvat equations rely on?
Constant / uniform acceleration
15
Suvat no s
V = u + at
16
Suvat no v
S = ut + 1/2 at^2
17
Suvat no a
S = u+v / 2 x t
18
Suvat no t
V^2 = u^2 + 2as
19
Momentum
Incl unit
Mass x velocity
Kgms-1
20
F (concerning momentum )
Change in mv / change in t
21
F (suvat)
And when does it work
F=ma when mass is constant
22
Impulse
Change in momentum
23
F x change in t
Change in mv
Where F is constant
24
change in Ep (GPE)
MgΔh
25
Ek (KE)
1/2 mv^2
26
Energy transferred , W
Fs cosθ
27
Rate of doing work =
Rate of energy transfer
28
P = ( 2 parts)
ΔW / Δt = Fv
29
Efficiency
Useful output power / input power
30
Hooke's law (2 ways)
F is directly proportional to ΔΧ
OR
F = kΔX
31
Young's modulus + unit
Tensile stress / tensile strain
Nm-1
32
Stress and unit
F/A
Pa
33
Strain
Extension / original length
34
Springs in parallel total x
1/2 x of one spring
35
Springs in series total x
2x of one spring
36
Density
Mass / volume
37
F using l
F = kΔl
K is the stiffness and the spring constant
38
Energy stores in a stretched spring
Incl relevance to a graph
1/2 F ΔL = area under force extension graph (elastic strain energy)
39
De Broglie wavelength
λ = h/p
40
Photon energy of a particle
E = hf
41
