Summary Of Science Review Questions And Answers From The Second Volume Of The Fifth Grade Primary School Textbook Published By The Xinshi District Educational Science Edition

Xinshi District Educational Science Edition Primary School Science Volume 2 Review Questions for Grade 5 1. Fill in the blanks: 1. When you press down the foam on the water surface with your hands, you will feel an upward force. This force is buoyancy. The sinking and floating of an object in water is related to the amount of water it displaces. Submarines achieve ups and downs by changing their weight by adding or subtracting water while keeping their volume constant. 2. The working principle of the thermometer is to utilize the thermal expansion and contraction properties of liquids. 3. When installing wires in summer, the wires between the two poles should not be pulled too tightly, otherwise in winter the wires will shrink due to cold and the wires will be easily broken. 4. When heat is transferred, it starts from the heat source and transfers from the hot end to the cold end. The further away from the heat source, the longer it takes for heat to transfer. Generally speaking, metals have stronger heat transfer capabilities than non-metals. 5. After the ancient Greek astronomer Ptolemy proposed the "geocentric theory", the Polish astronomer Copernicus proposed the "heliocentric theory" in his book "On the Revolutions of the Celestial Bodies". 6. The volume of water displaced by an object in water is called the amount of water displaced. 7. An instrument that compares the volume of a liquid is called a hydrometer. 8. The volume of water expands when heated and contracts when cooled. We call this change in the volume of water thermal expansion and contraction. 9. Heat is always transferred from the hotter end to the cooler end. Transferring heat from one object to another through direct contact is called heat conduction. 10. The gravity of a sinking object measured in air is 7. 5N, the gravity measured in liquid is 5N, and the buoyancy force it experiences is 2. 5N_. 11. A buoyant object's own gravity is 2N. If a force of 6N is used to press it into the water, the buoyant force it experiences will be 4N. 12. Write down the names of famous scientists in the process of people understanding the history of the earth. (At least three) Ptolemy, Bruno, Copernicus. 13. As time changes, the length and direction of the shadow of an object in the sun will slowly change. 14. Through my repeated experiments, I found that the number of times the pendulum swings back and forth per minute is related to the length of the pendulum, and has nothing to do with the amplitude or weight of the pendulum. 15. Objects with good thermal conductivity like metal are called good conductors of heat, while objects with poor thermal conductivity like plastic and wood are called poor conductors of heat. 16. Objects made of different materials, if they have the same volume, heavy objects will sink easily; if they have the same weight, small objects will sink easily. 17. The sundial uses light and shadow to keep time, the water clock uses the isochronous principle of dripping water to keep time, and the emergence of the pendulum clock improves the accuracy of timekeeping. 18. There are three ways of heat transfer: thermal conduction, convection, and thermal radiation. 19. The standard time currently adopted in our country is Beijing time. 20. The alternation of day and night is caused by the rotation of the earth, and the change of seasons is caused by the revolution of the earth. 21. The direction of the earth's rotation is from west to east, and the direction of the earth's revolution is from west to east. 22. Generally, the volume of an object expands when it is heated, and shrinks when it is cooled. We call this change of an object thermal expansion and contraction. 23. When the Earth rotates, its axis is always tilted toward the North Star. This is the secret of Polaris’ “immovable” state. 24. A stone is hung on a spring dynamometer. When weighed in the air, the spring dynamometer reads 4.7 N. When it is weighed completely immersed in water, the spring dynamometer reads 2.7 N. The buoyant force of the water on the stone is __2 N__. 25. The longitude passing through the Greenwich Observatory is designated as the 0 degree longitude. 2. True or False Questions: 1. The medicine ball sinking at the bottom of the swimming pool does not experience the buoyancy of the water. (×)