Define speed
distance travelled per unit
time
v=s/t
Define velocity
speed in a given direction
Define acceleration
change in velocity per
unit time
a = ∆v/∆t
List 6 scalar quantities
distance, speed, time, mass, energy and
temperature
List 6 vector quantities
force, weight, velocity, acceleration,
momentum, electric field strength and
gravitational field strength
Define gravitational field strength
force per unit mass
g=W/m
Define density
mass per unit volume
p=m/V
Define the spring constant
force per unit extension
k=F/x
Define the moment of a force
moment = force × perpendicular distance from
the pivot
Define momentum
mass × velocity
p = mv
Define impulse
force × time for which force acts
impulse = F∆t = ∆(mv)
Define resultant force
the change in momentum per unit time
F = ∆p/∆t
Define efficiency
(a)
(%) efficiency = (useful energy output)/(total energy input) (× 100%)
(b)
(%) efficiency = (useful power output)/(total power input) (× 100%
Define power
work done per unit time and
also as energy transferred per unit time
(a) P = W/t
(b) P = ∆E/t
Define pressure
force per unit area
p=F/A
Define specific heat capacity
the energy required per unit mass per unit temperature increase;
c =∆E/m∆θ
Define refractive index, n.
the ratio of the
speeds of a wave in two different regions
Define ultrasound
sound with a frequency
higher than 20kHz
Define electric current
the charge passing a
point per unit time
I=Q/t
Define electromotive force (e.m.f.)
the electrical work done by a source in moving a unit charge around a complete circuit
Know that e.m.f. is measured in volts (V)
E=W/Q
Define potential difference (p.d.)
the work done by a unit charge passing through a component
Know that the p.d. between two points is
measured in volts (V)
V=W/Q
Define the half-life of a particular isotope
the time taken for half the nuclei of that isotope
in any sample to decay
Define average orbital speed
v =2π r/T
where r is the average radius of the orbit and T is the orbital period
Define the Hubble constant H0
the ratio of
the speed at which the galaxy is moving away
from the Earth to its distance from the Earth;
recall and use the equation
H0 =v/d
