  Time series of string tension of a simple pendulum has not yet been a
interesting motion information, even nowadays using a force tension sensor can
be measured easily. A numerical procedure is presented how to obtain motion of
pendulum bob from the string tension. Unfortunately, proposed procedure does
not work. A quadratic term of \omega loses the sign of \omega that prevents the
procedure to work. Applying sign of string tension into the procedure can
produce the time series but only in positive value. The error for reproduced
angular displacement is about 7.6%.
