It is found that: ① the lower surface of the wood block is subjected to water pressure;
(2) Buoyancy of wood blocks;
Please find another physical quantity according to the conditions given in the question.
2. (Liaoning Province, 2003) As shown in figure 17, the weight of wood blocks in the air is 6n; When the 3/5 volume block is immersed in water, the pointer of the spring dynamometer is just right. Question: (1) What is the density of the wood block? (2) If the wood block is removed from the spring dynamometer and gently put into the water, how much vertical downward pressure can be exerted on the wood block to make it just completely immersed in the water? (g = 10N/kg)
4. There is a piece of wood hanging under the spring scale, which weighs 17 cattle in the air; When placing wooden blocks
Cattle/kg) q:
(1) What is the density of the wood block?
(2) If the wooden block is removed from the spring scale and put into the water, how much downward pressure does it have to bear to make it just completely immersed in the water?
5. The cylindrical container has a bottom area of 500 cm2 and contains water with a depth of 8 cm. Now put a cuboid block with a mass of 1.8kg and a bottom area of 100 cm2 into the container, and the liquid level will rise by 2cm.
Find (1) the pressure of the wood block on the bottom of the container.
(2) Fill the container with water slowly. How many kilograms of water should be added at least to make the pressure of the wooden block at the bottom of the container zero. (take g = 10N/kg)
6. Environmental protection is a hot spot in modern society, and environmental pollution is the focus of attention all over the world, especially nuclear pollution, which is a highly vigilant issue for all mankind. Following the 1986 Chernobyl nuclear accident, on August 12, 2000, the Russian nuclear submarine "Kursk" with the mass of m= 1.4× 107 kg was killed in the Barents Sea, which aroused widespread concern of Norwegian ecological protection organizations and the international community.
(The density of seawater is approximately ρ = 10N/kg)
(1)(4 points) The detection expert can detect the exact position of the submarine with ultrasonic waves. The wave velocity of ultrasonic wave in seawater is v = 1450m/s, and just before the submarine stops, the ultrasonic wave is emitted downward on the sea surface. The time from ultrasonic emission to submarine echo is t = 0. 146s, so the actual depth h of submarine sinking is probably a lot. (integer value)
(2)(5 points) Through research, one of the salvage schemes of Kursk is to wrap a large-load inflatable buoyancy bag around the submarine. If the inflation volume of each buoyancy bag is v0= 10 m3, how many buoyancy bags are needed?
(3)(4 points) According to the international practice of beach rescue, Norwegian divers arrived in Kursk on the night of August 19 and opened the emergency escape hatch. If the hatch cover area S=0.5 m2, what is the pressure f of seawater on the hatch cover?
(4)(4 points) Rescuers found a "black box" on the Kursk to record all kinds of submarine information, and the readings of three voltmeters on the shell of a component were U 1, U2 and U3 respectively; The expression of the mathematical relationship between I 1, I2 and I3.
7. As shown in Figure 24 (A), the metal block A is on the water block B, and the wood block is just immersed in the water. The metal block is put into water, and the supporting force of the bottom of the container to the metal block is 2n; As shown in fig. 24 (b), when the wood block is at rest, 2/5 of its volume is exposed to water. It is known that the volume of wood blocks is five times that of metal blocks. Find the density of metal and the gravity of wood block. (g = 10N/kg) (5 points)
8. As shown in Figure 20, it is known that the density of cube A is 0.8 g/cm3 and the volume is125 cm3; The contact area between cuboid B and the desktop is 100 cm2, and the pressure of cuboid B on the desktop is 700 Pa. According to the above conditions, besides the side length and surface area of cube A, some related physical quantities can be obtained. Please calculate any four physical quantities and fill in the calculation process and results in the table below. (g = 10N/kg)
9.(5 points) As shown in Figure 17, a miner grabbed one end of the rope with a horizontal pulling force of 200 N, moved to the right at a uniform speed along the horizontal ground, and lifted an object with a mass of 32 kg in the mine for 4 meters within 10 second. Please calculate five physical quantities related to this question according to the given conditions, and write a brief explanation and results. (g = 65440)
10, as shown in figure 19, the cube floats on the water, and 1/5 of the total volume is exposed out of the water, and the inextensible lifting rope is in a relaxed state. It is known that the maximum tensile force that the rope can bear is 5N, the pulley side length is 0. 1m, the bottom area of the container is 0.03m2, and there is a valve K at the bottom of the container. (2) Open the valve to make the water flow out slowly, and close the valve when the rope is about to break. What is the volume of boiling water discharged by the wood block at this time? (3) How does the water pressure at the bottom of the container change when the wooden block floats again after the string is broken compared with the moment before the string is broken? How much has it changed? (g = 10N/kg。 Tip: The two forces that interact are always equal. )
1 1. Both Party A and Party B use the horizontal thrust of 100 N to push two different tables A and B resting on the horizontal ground respectively. A moved table A by 1 minute, but B didn't push it. Q:
(1) What is the friction between the ground and desk A? What is the direction?
(2) How much work did A and B do respectively?
(3) What rights do Party A and Party B have within 1 minute?
13. There are some experimental equipment (as shown in figure 12) and enough water on the table. Please use these equipment to roughly measure the density of gravel. Requirements: (1) Write out the experimental steps simply. (2) Use the measured value to express the density of the stone.
17. Completely immerse the object suspended on the spring dynamometer in the container filled with water (without touching the bottom and side walls of the container), 0. 24 kilograms of water overflowed. The indicator of the spring dynamometer is1.2n. Please find out as many related physical quantities of the object as possible. (g = 10N/kg； Correctly find out four possible full marks) (Jinan, 2003)
18, electric bicycles are light, safe and pollution-free, and are deeply loved by people. On the weekend, a classmate rode an electric bicycle to the seaside and Liandao for sightseeing, passing through Lianyungang seawall levee, which was 7000m long and was called "the first levee in China". If the electric bicycle travels at a constant speed of 18km/h, the traction power of the electric bicycle is150W. Q:
(1) Time required for students to cross the levee;
(2) The work done by the electric bicycle through the overall traction of the levee;
(3) Electric bicycle traction.
19. (Ningde City, Fujian Province, 2004: A little open) Not long ago, two ships collided at the mouth of the Minjiang River, causing a cargo ship to sink to the bottom of the river dozens of meters deep. Suppose there is a sealed safe with a volume of 0.02m3 and a weight of 500N on the sunken ship. At present, the safe is pulled up from the bottom of the river with a rope at a constant speed, and lifted within 50 seconds 10m (not exposed to the water). In this process: (g is 10N/kg, regardless of water resistance).
(1) What is the buoyancy of water and the pull of the rope on the safe?
(2) How fast has SAFE risen?
(3) How much work has tension done?
20. As shown in figure 16, cube A with a side length of 0. 1m weighs 30N, and is placed on a horizontal ground, pulled by a horizontal pulling force F, and moves in a straight line at a uniform speed on the horizontal ground. It is known that the resistance of an object in motion is 0.0 1 times the weight of the object. (g takes 10n/kg) and finds:
(1) What is the pulling force f?
(2) What is the pressure of cube A on the horizontal ground?
(3) As shown in Figure 17, if Cube A is put into a water container, what is the buoyancy of Cube A?
(4) In addition to the above three questions, please ask another question and answer it.
2 1. As shown in figure 16, the massless smooth wooden board AB is 1.6m long and can rotate around the fixed point O. A weight G is hung at the B end 0.4m away from the O point, and the A end of the wooden board is pulled with a thin rope, making an angle of 30 with the horizontal ground. When the board is balanced in the horizontal position, the tension of the rope is 8N. Then put a ball with a mass of 0.5kg directly above the O point. If the ball moves from point O to end A along the chessboard at a uniform speed of 20 cm/s, ask how long it will take for the ball to move at least before the tension of the line decreases to zero. (take g= 10N/kg, regardless of the gravity of the rope)
22. There is amazing pressure in seawater. Every time the depth increases10m, the pressure will increase1.03x105pa. The deepest part of the ocean is the Mariana Trench in the Pacific Ocean, and the echo time of sonar detection is15.8s. The marine survey confirmed that there are still deep-sea fish here.
(1) Density of seawater.
(2) the depth of the groove.
(3) The pressure of seawater at the bottom of Mariana Trench on deep-sea fish.
(4) If this kind of deep-sea fish can be caught, can it be farmed artificially? Explain why. (Let the sound propagation speed in seawater be v = 1450m/s and g = 10N/kg).
23. A cylindrical container with a bottom area of 100 cm 3 is filled with a proper amount of liquid and placed vertically on a horizontal table. Put the wood block A into the liquid in the container. When it is still, one fifth of the volume of the wood block A is exposed to the liquid surface, and the depth of the liquid is 20 cm. If the metal block B is placed on the wood block A, the wood block A just sinks into the liquid surface, as shown in Figure 20. It is known that the volume of wood block A is 20 cm.
(l) Gravity on metal block B (2 points)
(2) When the wood block A just sinks into the liquid level, the pressure of the liquid on the bottom of the container (2 points)
As shown in Figure 9, a container is placed on a horizontal table and contains some liquid. The volume of the liquid is 2.0× 10-3m3, and the depth of the liquid is 0.5m If the container weighs 20 N, the bottom area is 2.0× 10-3m2, and the pressure at the bottom of the container is 5.0× 103 Pa. Q:
(1) Density of liquid.
(2) The liquid pressure at point A 0.2m away from the bottom of the container.
(3) The pressure of the liquid container on the desktop. (g = 10N/kg)
25. (Guangxi 2003) The length: width: height of brick is 4: 2: 1. If it is laid flat on a horizontal table top and 1/4 of the brick protrudes from the table top, the pressure on the table top is 1800Pa. What is the pressure on the ground when the brick stands on the flat ground?
26. As shown in the figure, a cylindrical container with a valve at the bottom has a bottom area of 4× 10-2m2 and a height of 0.24m A cubic block with a side length of 0. 1m floats in a container filled with water, and the depth of immersion of the block in the water is 0.06m Q: (1) (2) the pressure of water on the bottom of the container; (3) Open the valve and let some water flow out. How much water can flow out if the supporting force of the container bottom to the wood block is zero? (g = 10N/kg)
27. Gently put the solid cube with the side length of 10 cm into a large beaker filled with water. When the block is at rest, 600g of water overflows from the cup, as shown in figure 19.
Find: (1) buoyancy of wood block;
(2) density of wood blocks;
(3) The pressure of water on the lower surface of the block. (g = 10N/kg)
28.(6 points) Put a cubic iron block with a side length of 8 cm into a container filled with water and silver with a depth of 3 cm, and ask how much buoyancy the iron block receives. (ρ Hg = 13.6× 103kg/m3, ρ Fe = 7.9× 103kg/m3, g = 10N/kg).
29. The gravity of a piece of ore is measured to be 22 N with a spring scale, and the ore is immersed in water and weighed. The pointer of the spring scale is18n; Immerse the ore in another liquid and then weigh it. The pointer of the spring scale is 18.8 N, and find the density of this liquid. (g = 10N/kg)
30. The solid cube (which does not absorb water) floats on the water surface, as shown in Figure 13. At this time, the volume immersed in water is 600 cm3. (g = 10N/kg)
Findings: ① Buoyancy of wood block.
(2) Put an iron block weighing 4 Newton on the pad. After the block is stationary, the upper surface of the block is just flush with the water surface. What is the density of the block?
(3) After placing iron blocks on the wood blocks, how much does the water pressure on the lower surface of the wood blocks increase compared with that without iron blocks?
3 1. As shown in Figure 20, a stone with a weight of 3N and a volume of 100cm3 was tied with thin iron wire and immersed in a cylindrical container filled with water, and the depth of water in the container increased from 10cm to 12cm. (Ignoring the gravity of the container and the thickness of the container wall, g= 10N/kg) Find: (1) the buoyancy of the stone; (2) the gravity of water in the container; (3) The pressure of the container on the horizontal ground after the thin thread is loose and the stones sink into the bottom of the container and stand still.
32. (Xiangtan City, 2003) A classmate attached a uniform glass tube with openings at both ends to the lower end, and then used external force F to vertically insert the glass tube 25cm underwater.
Keep the balance, as shown. It is known that the cross-sectional area of the plastic sheet and the cross-sectional area of the glass tube are 10cm2, and the gravity on the glass tube is 0.5N, regardless of the thickness of the plastic sheet and the glass tube. Q:
(1) pressure and water pressure on plastic sheet;
(2) the magnitude of external force f.
(3) In order to measure the density of liquid, students first put the glass tube in water.
The position of the glass tube remains unchanged, and then the liquid is slowly poured into the glass tube. When the pouring depth reaches 20em, it is found that the plastic sheet just falls, so what is the density of the liquid?
33. (Nanning, 2003) As shown in figure 19, a cube with a side length of 0. 1m is placed in a container. Now water is slowly and continuously injected into the container. After a period of time, the density of the block is 0.6× 103kg, and g is 10n/kg. Q:
(1) What is the gravity on the block?
(2) When the water level in the container rises to the maximum height, the wooden block just floats?
(3) What is the pressure of water on the bottom of the container when the block just floats?
(4) When the water level in the container rises to 0.2m, what work does buoyancy do to the wood block during water injection?
34. (Nanning, 2004) Figure 1 4 is a schematic diagram of automatic drinking fountains for livestock. A is the water storage tank and k is the water outlet. Its cross-sectional area is 6 × 10-4m2. There is a piston at the water outlet, and the pressure of water is 5 × 103 Pa. The thin rod 0C can rotate around the zero point, and the distance from the zero point to the center of the floating ball is twice as long as the distance from the O point to the B point. Dangfu
When the volume of the ball is immersed in water 1/3, the thin rod oc is horizontal, and the piston at K can close the water outlet. (g = 10n/kg, ρ water = 1.0× 10N/kg/m3)
Q: (1) The piston bears water pressure.
(2) If the gravity of piston rod KB, thin rod 0C and float ball is not considered, what size float ball should be selected?
35, a uniform dry wood block, hanging under the spring dynamometer, spring dynamometer reading is 45 n.. When an object floats on the water and stands still, its exposed volume is 1/4 of the whole volume (water density ρ water = 1× 103kg/m3, g = 10n/m3. Q:
(1) Density of dry block.
(2) Hang the wood block in the spring dynamometer and put it into the water. What is the indication of the spring dynamometer when the submerged volume of the object is half of the whole volume?
36. Put a cube with a side length of 1dm and a mass of 2.7kg into the water of a cylindrical container with a bottom area of 4× (as shown in Figure 15). There is enough water and the container is deep enough. How much will the water pressure at the bottom of the container increase when the object is still in the water?
37. (Henan, 2004) After learning buoyancy, Xiao Liang made an experiment to observe the suspension of eggs. * * The main operation steps are as follows: as shown in figure 14, firstly, put a cylindrical container with a bottom area of 100cm2 (the thickness can be ignored) on a horizontal table, and inject 10cm into the container. Gently put it into the water and find that the egg sinks to the bottom of the container. At this time, the measured water level rose by 5 mm Then, salt was added to the container and stirred continuously until the eggs just floated. Please calculate.
(1) What is the pressure of water on the bottom of the container when eggs are put into the container (g= 10N/kg)?
(2) What is the density of salt water when eggs are suspended?