gravity pendulum造句

So this equation can be seen as a version of the equation for a simple gravity pendulum with a length equal to the radius of the Earth.
The precision of the early gravity measurements above was limited by the difficulty of measuring the length of the pendulum, " L " . " L " was the length of an idealized simple gravity pendulum ( described at top ), which has all its mass concentrated in a point at the end of the cord.
It's difficult to find gravity pendulum in a sentence. 用gravity pendulum造句挺难的