## Constrained Ball

from 2010.05.18 22:52

Let’s draw a straight line with the ball restricted in its direction. The length of the line can be measured accurately by calculating the turns of the wheel. Also, the accurate dimension of the straight line can be made as it is wanted. It is easy for fixing the inserted pen because the hole part is made of rubber in high elasticity. We can underline on the book and make a table and straight line in desired length can be drawn.