|
Sci Tech
Breaking a short stick
PHOTO:S. THANTHONI
Unlike a long stick why is it difficult to break a short stick with our hands?
Sapna Prasad
Chennai
Breaking a stick by hands involves bending the stick until it breaks.
A stick can be taken as an assemblage of woody fibres bundled into a compact structure. When it is bent, the fibres on the far side experience tensile force while those on the near side undergo compression leaving a neutral layer in between unaffected.
Both the tensile and compressive forces oppose the bending. Thus we need to keep the bending point, somewhere in the middle, fixed while a force is applied on the ends which come closer affecting the necessary bending.
Such a bending procedure may be viewed as folding of a hinged joint about the hinge, in which the motion is rotational motion. Such a rotational motion is the result of the moment of a force about the fixed point, the pivot, about which the rotation takes place. And the moment of a force is the product of the force and the perpendicular distance of the force from the pivot.
More the moment, easier it is to affect the rotation or bending. The moment can be increased either by increasing the force or by increasing the distance of application of the force. Instead of the difficult choice of applying larger force, it is preferred to increase the length of the arm.
In the case of the bending of the stick, the moment in question is the product of the force applied by our hands times half the length of the stick. Therefore, in the case of a long stick the moment is higher as compared to the case of a short one. In order to break a short stick by bending would require application of larger force as compared to breaking a long stick.
Dr. H. K. Sahu
Scientific Officer, IGCAR
Kalpakkam, Tamil Nadu
Printer friendly
page
Send this article to Friends by
E-Mail
Sci Tech
|
