<s>
Step	O
is	O
an	O
open	B-Application
source	I-Application
two-dimensional	O
physics	O
simulation	B-Application
engine	O
that	O
is	O
included	O
in	O
the	O
KDE	B-Language
SC	I-Language
as	O
a	O
part	O
of	O
KDE	B-Language
Education	I-Language
Project	I-Language
.	O
</s>
<s>
It	O
includes	O
StepCore	O
,	O
a	O
physical	O
simulation	B-Application
library	O
.	O
</s>
<s>
The	O
program	O
is	O
licensed	O
under	O
the	O
terms	O
of	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
,	O
making	O
it	O
free	B-Application
software	I-Application
.	O
</s>
<s>
Bodies	O
range	O
from	O
tiny	O
particles	O
to	O
huge	O
polygons	O
,	O
and	O
each	O
body	O
has	O
unique	O
properties	O
that	O
influence	O
the	O
outcome	O
of	O
the	O
simulation	B-Application
,	O
such	O
as	O
mass	O
and	O
velocity	O
,	O
and	O
their	O
derivations	O
such	O
as	O
kinetic	O
energy	O
.	O
</s>
<s>
Step	O
allows	O
reverting	O
after	O
simulation	B-Application
,	O
so	O
the	O
user	O
can	O
modify	O
the	O
bodies	O
and	O
forces	O
and	O
see	O
how	O
the	O
outcome	O
of	O
the	O
simulation	B-Application
is	O
affected	O
.	O
</s>
