

Acceleration
is how much your velocity changes each second
Velocity is measured
in metres per second (m/s),
so acceleration is measured in
metres per second per second (written as m/s/s or m/s)
No, it's not
a misprint, it's really called that.
It's how much your velocity (metres per second), changes each second
(per second).
We work out acceleration
using
Example:
a car accelerates from 8 m/s to 20 m/s, and takes 6 seconds to do
it.
What is the acceleration?
Answer:
change in velocity is 20 minus 8 = 12 m/s. Time taken for change
is 6 seconds.
Acceleration
= 12 divided by 6 = 2 m/s/s (that's a pretty
impressive car!)

Force
and acceleration:
If the forces on an
object are in balance, then its velocity will be constant (see
Forces page)
If
the forces aren't in balance, then the object will accelerate  which
may mean speeding up, slowing down, or changing direction.
 If we apply
an unbalanced force to an object, it will accelerate.
 If we apply
twice the force, we'd expect to get twice the acceleration.
 If we apply
the same force to an object with twice the mass, we'd expect
to get only half the acceleration.

Need to work out how
much it accelerates? See the bottom of this page
Advanced:
We have more flexibility
to cope with the calculations if we use an equation:
Where a
= acceleration (m/s/s)
v
= final velocity (m/s)
u
= initial (starting) velocity (m/s)
t
= time (seconds)
Thus v  u is the change in velocity
Example:
a wombat falls out of a tree into a vat of custard. It accelerates
at 10 m/s/s, and falls for 5 seconds. How fast is it going when
it hits the custard?
Answer:
first, realise that the wombat starts from rest, so u = 0.
we
have: a = 10 m/s/s, t = 5 sec, and we want v.
,
so v = 10 x 5 = 50 m/s
(that's
just over 111 miles per hour. Wombat puree)

Newton's Second
Law tells
us how much an object accelerates if the forces are unbalanced. It comes
down to an equation:
F
= ma
where F
= force (in Newtons)
m
= mass of object (in kilogram)
a
= acceleration (in metres per second per second)
Example:
a guinea pig of mass 1 kg sits on a skateboard of mass 2kg. If
the skateboard is pushed, and accelerates at 4 m/s/s, how big
is the force pushing it?
Answer:
first, we need to add the mass of the guinea pig and the skateboard
together.
That's
1kg + 2kg = 3kg
we
know that acceleration = 4 m/s/s
using F =
ma, we have F = 3 x 4 = 12 Newtons
(hope
the guinea pig was holding on tight)

