The original length of a spring is 15cm, the mass part of the object it hangs can exceed 18kg, and the spring stretches 0.5cm for every 1kg of weight. The functional relationship between the spring length y (CM) and the mass x (kg) of the object after hanging is written, the value range of the independent variable x is explained, and its image is drawn

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• 1. The original length of a spring is 12cm, and it will extend 0.5cm for every 1kg of hanging weight, and its hanging weight shall not exceed 10kg 1. Find the functional relationship between the length y (CM) of the spring after hanging and the hanging weight x (kg) 2. Write the value range of the independent variable 3. When the hanging weight is kg, the length of the spring is 16.4cm?
• 2. One spring is 40cm long, one end is fixed, and the other section can be hung with heavy objects. Generally, when the weight of the object is increased by 1kg and the spring is extended by 2cm, the spring length is 45cm The mass of the hanging object is best solved by a linear equation of one variable
• 3. The relationship between the length y (CM) and the weight x (kg) of a certain spring with a length of 20cm, a weight of 1kg and an elongation of 0.2cm
• 4. The length of a spring without hanging a heavy object is 12cm, and the length of extension after hanging a heavy object is directly proportional to the mass of the suspended object; if a 1kg object is hung, the spring is extended by 2cm; the functional relationship between the total length of the spring y (unit: cm) and the mass x (unit: kg) of the suspended object is obtained
• 5. Use a light spring with original length l0 = 15cm to lift a wooden block vertically, and the length of the spring is L1 = 23cm. If the wooden block is pulled horizontally to move uniformly on the horizontal table, the length of the spring is L2 = 17cm. Calculate the dynamic friction coefficient u between the wooden block and the horizontal table. If the mass of the wooden block is m = 8kg, what is the light coefficient K of the spring?
• 6. On the horizontal table, pull a 200N wooden block to the right along the horizontal direction with a spring dynamometer at a constant speed, and the indication of the spring dynamometer is 50N 【1】 Try to analyze the force on the block, and the force diagram, and find out the size of the force 【2】 If the indication of the spring dynamometer increases to 60N, what is the friction force on the block? What is the resultant force on the block? What is the motion state of the block?
• 7. As shown in the figure, regardless of the mass of the plastic cup placed on the horizontal table, pour 200g water into the cup with a water depth of 20cm; then gently put 40g wood block into the cup, and the wood block floats after it is still, and the water surface rises by 4cm (water does not overflow, g = 10N / kg)? (2) What is the buoyancy of the block? (3) What is the pressure of the bottom of the cup on the horizontal table?
• 8. As shown in the figure, regardless of the mass of the plastic cup placed on the horizontal table, pour 200g water into the cup with a water depth of 20cm; then gently put 40g wood block into the cup, and the wood block floats after it is still, and the water surface rises by 4cm (water does not overflow, g = 10N / kg)? (2) What is the pressure of the bottom of the cup on the horizontal table?
• 9. Pour 200g water into the cup, the water depth is 20cm, put 40g wood block, the water surface rises 4cm, ask the pressure of water on the bottom of the cup? The pressure of the bottom of the cup on the table?
• 10. Fill the cup with water and put a small wooden block into the cup. The small wooden block floats on the surface of the water. After putting the wooden block, the pressure of the container on the table will not change
• 11. The length of a spring is 20cm when a 4kg object is hung. Within the elastic limit, the length of the spring is 1.5cm when the weight of the object is increased by 1kg. Write out the equation of the relationship between the length of the spring y (CM) and the weight of the object x (kg)
• 12. The length of a spring is 20cm when a 4kg object is hung. Within the elastic limit, the length of the spring is 1.5cm when the weight of the object is increased by 1kg. Write out the equation of the relationship between the length of the spring y (CM) and the weight of the object x (kg)
• 13. The length of a spring under 30n tension is 20cm. When the length under 20n pressure is 15cm, what is the original length and progress coefficient of the spring To be specific,
• 14. The length of a spring is 20cm under 30n tension and 19cm under 20n tension?
• 15. If the lengths of three sides of a triangle are 15cm, 20cm and 25cm respectively, the height of the longest side of the triangle is?
• 16. As shown in the figure, the original length of a spring is 20cm, which is suspended vertically. When the spring is pulled down vertically with 15N force, the spring length is 24cm; if it is erected on a horizontal table and pressed down vertically with 30n force, how long is the spring? (ignoring the self weight of the spring, the spring is always within the elastic limit)
• 17. What is the stiffness coefficient after the spring with stiffness coefficient K is divided into two equal parts and paralleled
• 18. Why is the stiffness coefficient of a spring related to its length? What is the root cause?
• 19. In the case of no wind, the raindrop falls vertically along a straight line in the air. The air resistance f is directly proportional to the square of the raindrop velocity, f = Kv2. If the mass of a raindrop is m, the maximum kinetic energy of the raindrop is
• 20. When an object with a weight of Mg falls vertically in the air, it is not only affected by gravity, but also by a resistance f which is proportional to the square of the velocity. Its size f = kV ^ 2, K is a positive constant. Then the final velocity of the falling object (that is, the velocity of the object when it finally moves at a constant speed) is______ ．