Download Year 13 Physics Epic Entire Year Equation, Symbol, Unit and

Level 2 Physics Epic Entire Year Equation, Symbol, Unit and Situation Worksheet ANSWERS
Equation
Symbol
Name and
SI unit
Applications or Situations where Equation is commonly used
Mechanics Section:
1.
v=
2.
3.
4.
5.
6.
Δd
Δt
v
a
t
v f  v i  at
d  v i t  12 at 2
v  vf
d i
t
2
2
2
v f  v i  2ad
7.
ac 
2
v
r
8.
F = ma
9.
  Fd
10.
F = - kx
11.
Fc 
mv 2
r
v
Δd
Δt
Velocity (ms-1)
Change in displacement (m)
Change in time (s)
a
Δv
Acceleration (ms-2)
Change in velocity (ms-1)
(ms-1)
1. Only to be used for constant speed (constant velocity).
Also can be used for “average velocity” with “total displacement” and
“total time”
2. Only used in 1D problems (NOT 2D!!!) Δv is vf – vi.
If one of the velocities is backwards ONE MUST BE NEGATIVE!!!
3,4,5,6. Assumes constant acc (no friction).
vf
vi
a
t
d
Final velocity
Initial Velocity (ms-1)
Acceleration (ms-2)
Time (s)
Distance (or displacement) (m)
ac
v
r
Centripetal acceleration (ms-2)
Tangential velocity (ms-1)
Radius of spin (m)
7. Assumes constant speed round circle.
F
m
a
τ
d
Net Force (N)
Mass (kg)
Acceleration (ms-2)
Torque (Nm)
Distance (force from pivot) (m)
8. Newton’s 2nd Law. Net (resultant or total) force proportional to
acceleration.
Same direction (F and a)
9. Also known as “moment”. F and d must be 90°.
F
k
x
FC
m
v
r
Restorative Spring Force (N)
Spring Constant (Nm-1)
Extension (m)
Centripetal Force (N)
Mass (kg)
Velocity (ms-1)
Radius (m)
Used for 1D situations (or vertical part of projectiles) ONLY. Watch out
for negatives (acc or vf or vi) if opposite directions are involved.
With free-fall: acc = gravity (given on exam)
Acc towards centre of circle with velocity tangent to circular path.
Two possible directions (clockwise, anti-clockwise)
10. Hooke’s Law: Negative since F opposes extension.
Can be linked to F=mg with Newton’s 3rd Law.
Stiffer spring = bigger k
11. Force to centre of circle (same direction as ac). Can link with F=ma.
v2
2r
This is combination of F=ma and ac 
. Can include v 
.
T
r
12.
p  mv
13.
Δ p = FΔ t
14.
Ep  12 kx 2
15.
Ek  12 mv
2
16.
ρ
Momentum (kgms-1)
Δρ
F
Δt
EP
k
x
Ek
m
v
Δ Ep
Impulse (kgms-1)
Contact force (N)
Time of contact (s)
Elastic Potential Energy (of spring) (J)
Spring constant (Nm-1)
Extension (m)
Kinetic Energy (J)
Mass (kg)
Velocity (ms-1)
Change in Gravitational Potential
Energy (J)
Gravity (acceleration) (ms-2)
Height (m)
Work (change in energy) (J)
Net force (N)
Distance moved (m)
Power (W)
Work (change in energy) (J)
Time (s)
Δ E p = mgΔ h
17.
18.
W  Fd
P
W
t
g
h
W
F
d
P
W
t
12. Needs DIRECTION. Can be 1D or 2D. 2D requires triangles!
Used in Conservation of Momentum (total before = total after)
Negative momentum vectors must be turned 180° and “added”
13. Alternative unit for kgms-1 (Ns). Can be paired with F=ma
Force used to change momentum (and speed) for impacts, crashes or
collisions.
14. Is a combination of F=-kx and area of triangle on F vs x graph.
Can be done with Ep = ½ F x
15. can be paired with Ep = mgh for energy conservation (assumes no
friction or energy-loss)
Used to find elastic vs inelastic collisions (no energy loss vs energy loss)
16. can be paired with W = Fd or Ek  12 mv 2 .
17. can be paired with any other energy equation. Net force must be
parallel to distance moved. Also used to find “average force to stop
objects”.
18. AKA “rate of energy used”. Alternative unit for Watt: Joule per sec.
Electromagnetism Section:
19.
E=
V
d
20.
F = Eq
E
V
d
Electric Field (Vm-1)
Voltage (V)
Distance (m)
F
E
q
Electric Force (N)
Electric Field (NC-1)
Charge (C)
19. Usually for E-field between capacitor plates of voltage V and
distance of separation d. Alternative unit for E-field: (NC-1)
Has DIRECTION: E-filed from + to – and shows direction a + charge
would move if inside E-field.
20. Usually for electric force on electron or dust in between capacitor
V
plates. Can be paired with E = .
d
AND used of Millikan’s experiment with F=mg
Δ Ep
21.
E
d
Change in electrical potential energy
(J)
Electric Field (Vm-1) or (NC-1)
Distance moved (m)
I
t
Current (A)
Time (s)
V
ΔE
Voltage (potential difference) (V)
Change in energy (work) (J)
V
I
R
P
Voltage (V)
Current (I)
Resistance (Ω)
Power (W)
Δ E p = Eqd
22.
23.
24.
25.
q
t
ΔE
V=
q
I=
V  IR
P  IV
21. Used for charged bits in electric field (test charges). Energy gained
or lost as charged bits move through E-field or across potential lines.
Test charge usually assumed to be positive.
+ charge moved to higher potential: GAINS energy
- charge moved to higher potential: LOSES energy
22. Definition of electrical current – “flow of charge” or “rate of flow of
charge”. Conventional Current: from + to -. Electron flow opposite way.
23. Definition of potential difference (voltage): energy changed from
electrical potential to light/heat as charge passes. Can be used to find
energy lost or gained by charge crossing potential lines.
24. Ohm’s Law: technically only for ohmic resistors: straight, diagonal
line on V vs I graph (with R = slope).
25. aka “rate of change of energy” and can be paired with P =
V  IR . There are 2 more equations possible: P 
26.
P=
ΔE
t
27.
29.
30.
1
1
1


 ...
RT R1 R 2
F  BIL(sinθ )
F  Bqv
V2
and P  RI 2
R
P
ΔE
Power (W)
Change in energy (work) (J)
26. see above (#25)
RT
Total resistance (series) (Ω)
RT
Total resistance (parallel) (Ω)
F
B
I
L
θ
q
v
Lorentz Force (N)
Magnetic Field (T)
Current (A)
Length of wire in B-field (m)
Angle between B and I (°)
Charge of particle (C)
Velocity of particle (ms-1)
27. ONLY for series circuit resistors. Can be used in complex circuits
but only AFTER parallel bits have been simplified and reduced to
equivalent series resistors.
28. ONLY for parallel circuit resistors. If a “row” has more than one R in
series they must be added BEFORE using the equation.
29. Uses Right-Hand-Slap-Rule: thumb = I, fingers = B, palm = F.
RT  R1  R2  ...
28.
ΔE
or
t
Force involved in electric motors and current carrying wire in B-fields.
“Current in B-field causes F”
30. Also the Lorentz Force (like #29) but for charged particles shot into
B-field at velocity. Uses Righ-hand-slap rule: fingers = B, palm = F BUT
thumb = motion of POSITIVE particle.
If negative particle – must have thumb pointing opposite direction to
particle’s velocity.
31.
V  BvL
V
v
L
B
Induced Voltage (V)
Velocity of wire (ms-1)
Length of wire crossing B-field (m)
Magnetic Field (T)
31. For “rail” pulled across B-field. F=BIL shows up as opposing force
with right-hand-slap-rule to determine direction of current. Usually with
galvanometer to show direction of current.
Commonly asked for “which side of rail is +?”. Must think of “rail” as
“battery”.
Wave Section:
32.
1 1
1


f do di
f
do
di
33.
So
si so = f
34.
35.
2
m=
d i hi
=
d o ho
m=
f si
=
so f
36.
n1 sin 1  n2 sin 2
37.
n1 v 2 λ 2


n2 v 1 λ 1
38.
v =fλ
39.
f 
1
T
Si
f
m
ho
hi
Focal length (cm) or (mm) or (m)
Distance from object to lens/mirror
(cm) or (mm) or (m)
Distance from image to lens/mirror
(cm) or (mm) or (m)
Distance from object to focal point
(cm) or (mm) or (m)
Distance from image to focal point
(cm) or (mm) or (m)
Focal point (cm) or (mm) or (m)
Magnification (no units)
Height of object (cm) (mm) or (m)
Height of image (cm) (mm) or (m)
32. All 3 must have same units. Focal length (f) negative for convex
MIRROR and concave LENS. di will be negative for VIRTUAL images.
Must remember to INVERSE before getting final answer.
Called “Descartes Formula”
33. Called “Newton’s Formula”. No negatives for this formula.
S’s can be to “near” or “far” focal point in lenses.
Convex lens: So to “near”, Si to “far”.
Concave lens: So to “far”, Si to “near”.
34. also called “Newton’s Formula”. No negatives needed. Can have
2 more fractions in same formula (see #35 below).
35. Usually paired with #34 above. Explains where #33 above comes
from
n1
θ1
n2
θ2
v
λ
Index of refraction #1 (no unit)
Angle of incidence (or angle #1) (°)
Index of refraction #2 (no unit)
Angle of refraction (or angle #2) (°)
Velocity of wave (ms-1)
Wavelength (m)
v
f
T
Velocity of wave (ms-1)
Frequency (Hz)
Period (s)
36. Snell’s Law: for refraction of light at flat boundary. Angles
measured from light ray to NORMAL. Must take inverse sine to find
angle. Also used for CRITICAL ANGLE when one angle = 90°
37. Used for “deep/shallow” refraction problems. Can have another
sin  2
fraction with
for angles of incidence and refraction.
sin 1
38. Can be used for any wave. For sound – f and λ must multiply to
speed of sound. For light f and λ must multiply to speed of light.
39. used to get frequency (number of cycles per second) from period
1
(number of seconds per cycle). Can be written as T 
f