درس الحجم

الحــــــجـــــــم

Le volume

 I– مفهوم الحجـــــــم :

نضع جسما صلبا في كأس به ماء.

- يحتل كل من الجسم الصلب و الماء و الهواء حيزا من الفضاء الداخلي للكأس ، و يسمى هذا الحيز : حجم الجسم.

- يرمز للحجم بالحرف V .

- الوحدة العالمية لقياس الحجم هي المتر مكعب ( m3 ).

- بالنسبة للسوائل تستعمل كذلك وحدات السعة وهي اللتر و مضاعفاتها وأجزاءها.

- سعة إناء هي حجم السائل الذي يمكن أن يحتويه عندما يكون مملوءا.

- يعطي الجدول التالي مختلف وحدات الحجم، والعلاقات بينها وبين وحدات السعة.

mm3                                                                                                                                                     cm3                                                                                                                                                     dm3                                                                                                                                                     m3                                                                                                                                                     dam3                                                                                                                                                     hm3                                                                                                                                                     km3

                                                                                                                                                                                                                                                                                                                                                                                                                                                               ml                                                                                                                                                     cl                                                                                                                                                     dl                                                                                                                                                     l                                                                                                                                                     dal                                                                                                                                                     hl                                                                                                                                                     kl                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

تطبيق:5 dam3 = 5000 kl و 1ml = 1 cm3 و 0.2cl = 2cm3 .

II– قياس حجم جسم سائل :

لقياس حجم جسم سائل نستعمل أواني مدرجة مثل : المخبار المدرج.

لتعيين التدريجة بدقة :

                                                                                                                                                     ينبغي أن تكون العين في وضع بنفس المستوى الأفقي لسطح السائل.

                                                                                                                                                     نصوب النظر إلى أسفل السطح الهلالي للسائل.

                                                                                                                                                     نقرأ القيمة الموافقة للتدريجة.

                                                                                                                                                     نكتب العدد الذي نقرأه متبوعا بوحدة القياس المسجلة على المخبار.

III- قياس حجم جسم صلب :

      1- قياس حجم جسم صلب ذو شكل ما :

لقياس حجم جسم صلب ذو شكل ما نستعمل مخبارا مدرجا و جسما سائلا .

                                                                                                                                                     نعين حجم الجسم السائل : V1

                                                                                                                                                     ندخل الجسم الصلب في المخبار المدرج.

                                                                                                                                                     نقرأ الحجم V2

                                                                                                                                                     نستنتج أن حجم الجسم الصلب هو :       V = V2 – V1

- قياس حجم جسم صلب ذو شكل هندسي بسيط

في هذه الحالة نقيس أبعاد الجسم ثم نحسب حجمه.