equations

Question 1

word, symbol and units of speed equation

Answer 1

speed = distance / time
s = d/t
s = ms^-1
d = meter
t = seconds

Question 2

word, symbol and units of acceleration equation

Answer 2

acceleration = final velocity - initial velocity / time
a = v -u/t
a = ms^-2
v = ms^-1
u = ms^-1
t = seconds

Question 3

word, symbol and units of force equation

Answer 3

force = mass x acceleration
F = ma
F = N
m = kg
a = ms^-2

Question 4

word, symbol and units of force (spring) equation

Answer 4

force = spring constant x extension
F = kx
F = N
k = Nm^-1
x = m

Question 5

word, symbol and units of weight equation

Answer 5

weight = mass x gravitational field strength
w = mg
F = N
m = kg
g = 9.8KgN^-1

Question 6

word, symbol and units of GPE equation

Answer 6

Gravitational potential energy = mass x gravitational field strength x change in height
GPE = mgh
GPE = J
m = Kg
g = 9.8Nm^-1
h = meters

Question 7

word, symbol and units of KE equation

Answer 7

kinetic energy = 1/2 x mass x velocity^2
KE = 1/2mv^2
KE = J
m = Kg
v = ms^-1

Question 8

word, symbol and units of work done equation

Answer 8

work done = force x distance
w = Fd
w = J
F = N
d = meter

Question 9

word, symbol and units of power equation

Answer 9

power = useful energy / time
power = useful work done/ time
P = E/w / t
P = E (energy)/ w(work done)
t = seconds

Question 10

word equation of efficiency

Answer 10

efficiency = useful energy/power / total energy/power x 100%

Question 11

word, symbol and units of pressure in solid equation

Answer 11

pressure = force / area
P = F/A
P = Pa / Nm ^2 / Ncm ^2
F = N
A = m^2 / cm ^2

Question 12

word, symbol and units of moment equation

Answer 12

moment = force x perpendicular distance from pivot
m = Fd
m = Nm
F = N
d = meters

Question 13

word, symbol and units of pressure in liquids equation

Answer 13

Pressure = height x density x gravity
P = hpg
P = Pa / Nm ^2 / Ncm ^2
h = m
p = Kg/ dm ^3
g = Nkg ^-1

Question 14

word, symbol and units of density equation

Answer 14

p = m / V
density = mass / volume
p = kgm ^-3 / gcm ^-3
m =kg
V =m ^3

Question 15

word, symbol and units of wave speed

Answer 15

V = fλ
velocity = frequency x wave length
V= velocity (ms^-1)
f=frequency (Hz)
λ= wave length (m)

Question 16

word, symbol and units of period

Answer 16

T = 1/ f
time = 1/ frequency
T= time (s)
f= frequency (Hz)

Question 17

Snell’s law

Answer 17

n = sin ( i angle ) / sin( r angle )

Question 18

3 formulas to find refractive index

Answer 18

• n = sin ( i angle ) / sin ( r angle )
• n = 1/ sin ( C - critical angle )
• n = c - speed of light in vacuum / speed of light in medium
  ( use sin^-1 if needed to convert to angle)

Question 19

word, symbol & units for magnification formula

Answer 19

-image distance from optic center/ obj distance from optic center
-no units & symbols

Question 20

word, symbol & units for power of lens formula

Answer 20

• 1/ focal length
• P = 1/ f
  P = m^-1
  f = m
  -positive for convex lens
  -negative for concave lens