Equations Glossary

These are most of the equations you need to know. If I have missed any out, please comment and let me know. Thanks!

(i) the relationship between average speed, distance and time: 

average speed= distance/time

s=d/t

   

(ii) the relationship between force, mass and acceleration: 

force = mass × acceleration 

acceleration = change in velocity/time taken

a=v-u/t

   

(iii) the relationship between density, mass and volume: 

density=mass/volume

ρ=m/v

   

(iv) the relationship between force, distance and work: 

work done = force × distance moved in direction of force 

E=Fxd

   

(v) the energy relationships: 

energy transferred = work done 

kinetic energy = ½ × mass × speeds2

Ek= ½ x m x s2

gravitational potential energy = mass × g × height 

   

(vi) the relationship between mass, weight and gravitational field strength: 

weight = mass × gravitational field strength 

W=m x g

   

(vii) the relationship between an applied force, the area over which it acts and the resulting 

pressure=force/area

p=F/A

   

(viii) the relationship between the moment of a force and its distance from the pivot: 

moment = force × perpendicular distance from the pivot 

moment=F x d

(ix) the relationships between charge, current, voltage, resistance and electrical power: 

charge = current × time 

Q=Ixt

voltage = current × resistance 

V=IxR

electrical power = voltage × current 

P=VxI

   

(x) the relationship between speed, frequency and wavelength: 

wave speed = frequency × wavelength 

V(velocity)=f x λ

   

(xi) input (primary voltage)/output (secondary voltage)=primary turns/secondary turns

   

(xii) the relationship between refractive index, angle of incidence and angle of refraction: 

n=sin i/sin r

   

(xiii) the relationship between refractive index and critical angle: 

sin c = 1/n

   

(xiv) the relationship for pressure difference: 

pressure difference = height × density × g 

p = h x ρ x g