A rod fixed at one end may be put in transverse vibration by being struck or plucked at the free end - as in the music box. The longer the rod, the lower the tone produced.

Rods may be made to vibrate longitudinally as well as transversely.

Demonstrations. - Hold a glass rod, a meter long or more, by the middle with one hand, while with the other you draw a moist cloth lightly from the middle to the end. The rod will be thrown into longitudinal vibrations, and the fundamental tone will be produced. Do the same with a wooden rod, a brass rod, and a brass tube of the same length and diameter, using a rosined cloth for a rubber. Does the pitch of the tone depend upon the material of the rod?

Repeat the above demonstration with two glass tubes of different diameters, but of the same length. Does the pitch of the tone depend upon the diameter of the tube? Repeat with one of these tubes and another of the same diameter but only half as long. Does the pitch depend on the length of the tube? How do the two tones compare?

The sound caused by rubbing the tubes and rods in the above demonstrations is due to longitudinal vibrations. That such vibrations exist may be shown as follows:

Demonstration. - Clamp a brass rod firmly to a block upon a table as shown in Fig. 2. Suspend an elastic ball so that it will rest against one end of the rod, and then draw a rosined cloth from the middle to the other end.

The longitudinal vibrations will cause the rod to give out a high tone, and will repel the ball from the end of the rod.

The mechanical effect of vibrations in tubes is sometimes very great. It is not uncommon for a test tube to be cracked into a spiral ribbon running from end to end, on being wiped with a damp towel. If a glass bell jar is bowed vigorously a few times with a violin bow, it may be shattered even if the walls are a quarter of an inch thick.

اخر الاخبار

اخبار العتبة العباسية المقدسة

مؤتمر السيد المجاهد يشهد عرض فيلم وثائقي عن سيرته العلمية ومشروع إحياء تراثه

بحث حوزوي يتناول التمييز بين المعجزة والسحر عند السيد المجاهد

بحث يناقش أثر القواعد العقلية في استنباط الأحكام الشرعية عند السيد محمد المجاهد

بحث علمي يناقش ردود السيد المجاهد على اللغويين والنحويين في كتابه (مفاتيح الأصول)

المزيد

الآخبار الصحية

هل توقيت نشاطك اليومي يؤثر على صحة دماغك؟.. العلماء يجيبون

"مشروب محبوب" يخفي فوائد لا يعرفها كثيرون

طبيب يكشف 5 أنواع للسعال.. بعضها خطير

نقص فيتامينات "خفي".. قد يفسّر التعب والتنميل وقلة التركيز

المزيد

الآخبار التكنلوجية

دراسة: تغيّرات في أسلوب القيادة قد تكشف مبكرا عن الخرف !

عمرها 773 ألف سنة.. اكتشاف أقدم أحافير بشرية في المغرب

"اختراق علمي".. اختبار دم في منزلك قد يكشف ألزهايمر

ماذا يحدث للجسم عند قطع الكافيين فجأة؟

المزيد

مواضيع ذات صلة

The Wedge

The Law of the Screw

Systems of Fixed and Movable Pulleys

The Inclined Plane

The Screw

Application of the Screw

The Automobile

Gas Engines

Manometric Flames

The Pendulum Method traces the curve. Demonstration

Graphical Method of Combining Vibrations

The Vibration of Plates