The function is
.
The fleeing object leaves the origin and moves the up
-axis.
Substitute
.
.
The fleeing object is travelled
units when it is caught.
Definition Of Arc Length :
\ Let the function given by
represent a smooth curve on the interval
.
The arc length of
between
and
is
.
Where
is
.
The function is
.
Apply derivative on each side with respect to
.



.
Substitute
in
.

.




.
The distance travelled by pursuer is
.
The distance travelled by fleeing object is
.
Hence,
.
Therefore, the pursuer has travelled twice the distance travelled by the fleeing object.
\The pursuer has travelled twice the distance travelled by the fleeing object.