ساينس الصف الأول الاعدادي – الفصل الدراسي الاول ساينس اولي اعدادي ترم اول In This part we will study : According to the difference in density : • equal volumes of different substances have different masses. • Equal masses of different substances have different volumes. Conclusion : • Materials which have higher density than water sink in it such as an iron nail and a metallic coin. • Materials which have lower density than water float on its surface such as wood, cork, ice and drops of oil. Life applications of the density : 1. Water is not used to put out (extinguish) petrol fires. Because the density of petrol is less than that of water so, petrol floats on water surface and fire will increase 2. Balloons filled with hydrogen or helium rise up in the air carrying flags during festivals. Because the densities of hydrogen and helium are less than the density of air 3. The change in the density of matter is used to check the purity of matter as determination of the quality of milk. Give Reason: 1. Equal volumes of different materials have different masses. 1. Equal masses of different materials have different volumes. Because they have different densities 2. The cork & wood float on the water surface Because the density of wood & cork is less than the density of water. 3. The glass & Iron sinks in the water Because the density of glass and Iron is more than the density of water. لمتابعة مستر احمد الباشا وكل ما يخص الساينس : جروب الفيس بوك http://bit.ly/2Of1mcN صفحة الفيس بوك http://bit.ly/2Gq5xMo بالتوفيق مستر احمد الباشا