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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

Rest mass energy of a particle

E = mc^2