Bodies in Motion

When considering the motion of a body we often need to know details of its speed and the distance it has travelled. In some cases the nature of the motion is very complex and there is no alternative to an in-depth mathematical analysis or experimental measurement.

There are however many cases in which the motion is fairly simple, or can be approximated to a simple analysis. The equations below are for a body subject to a constant rate of acceleration (or deceleration)

v = u + a t

s = ( u + v ) t / 2

s = u t + 0.5 a t2

v2 = u2 + 2 a s

p = m v

E = 0.5 m v2

Symbol  
Units
u
Initial speed in metres per second
m s-1
v
Final speed in metres per second
m s-1
a
Acceleration (Deceleration if negative) in metres per second per second
m s-2
t
Time in seconds
s
s
Distance in metres
m
m
Mass in kilo-grams
kg
p
Momentum in kilo-gram metres per second
kg m s-1
E
Kinetic energy in Joules
J

 

 
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