"Classified Comprehensive Training" Buoyancy PPT

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"Classified Comprehensive Training" Buoyancy PPT

Part One: Breakthrough of Core Points

1. Buoyancy

1. Definition: An object immersed in __________ experiences a force called buoyancy by ____________ on it. Its direction is ________, and the object exerting the buoyant force is ___________.

2. Archimedes' Principle:_______________________________________________.

Expressed as _______________, the formula shows that buoyancy is only related to __________ and ____________, and the formula is applicable to _____ and _____.

3． Four ways to calculate buoyancy (write expressions)

(1) Pressure difference method: _____________.

(2) Principle method: ______________.

(3)Weighing method: ____________.

(4) Balance method: ________ (only applicable to "suspended" or "floating" state).

2. Floating and sinking conditions and applications of objects

4. Floating and sinking conditions

To determine the floating and sinking state of an object immersed in a liquid, you can judge by comparing the relationship between the ____ force and the ____ force on the object, or by comparing the relationship between the _____ density and the ____ density. to judge.

5. Utilization of buoyancy

(1) Ship: Made into ______ to increase the volume of liquid displaced, thereby increasing _____. The same ship is in a _____ state whether it is in the sea or in a river, so the buoyant force on the ship is _____ the gravity it experiences, so the buoyant force on the ship is _______.

(2) Submarine: float and dive by changing the ________. The process of ascent and descent is accomplished by a device _____. During the process of surfacing and submerging, the buoyancy force on the submarine is _____.

(3) Balloons and airships: The air bags are filled with gas of density ____ air, so that they can float in the air.

Comprehensive classification training PPT, the second part of the content: teaching material picture display

Proposition point 1 Buoyancy

(1) As shown in Figure 10-T-1, the apple sinking in the water is acted upon by ____ force and ____ force. Among them, the buoyant force exerting object is ____, and the direction is _________.

(2) When the apple is immersed in water, although it continues to fall, the buoyancy force it experiences is _____, because the apple ___________ remains unchanged.

Proposition 2: Perception of Archimedes' Principle

(1) Place the beaker filled with water on the plate and press the empty beverage can into the water. If you feel effort, it means that the empty beverage can is affected by ____ force.

(2) The deeper the empty beverage can is immersed in the water (not submerged), the more effort it feels. At the same time, the volume of water displaced by the empty beverage can is _____, and the buoyancy force it receives is _____.

Proposition point 3 The floating and sinking of objects

(1) The same fresh eggs are put into beakers filled with water and concentrated salt water respectively. If the egg sinks to the bottom in the water, it means that it is buoyant by ______ gravity. When the egg is suspended in concentrated salt water, it is said that it is buoyant by ______ gravity. .

(2) According to the formula ____________, it can be seen that when the eggs are immersed in two liquids, the volumes of the liquids displaced are the same and the g value is the same. Since the density of concentrated salt water is higher, the buoyancy force in the concentrated salt water is also higher. __.

Comprehensive classification training PPT, the third part: reproduction of key experiments

Experiment 1: Explore the factors that affect the size of buoyancy

(1) Experimental device: As shown in Figure 10-T-4.

(2)Experimental design

① During the experiment, it was found that the indication of the spring force gauge in Figure B was smaller than that in Figure A, indicating that block A was affected by _____.

② From Figures B and C, it can be seen that the buoyancy force experienced by block A after being immersed in water is increased by _____N compared with the buoyancy force experienced before being immersed. It can be seen that the buoyancy force experienced by an object immersed in liquid is related to _______________.

③In order to explore whether the buoyancy force is related to the density of the liquid, the operation that should be used is __________.

④In order to explore whether the buoyancy force is related to the depth of immersion of the object, the operation that should be used is __________.

(4) Expansion: After completing the above experiment, the students boldly guessed: "Is the buoyancy force on an object immersed in a liquid related to the density of the object?" Please help the students complete this investigation.

① During the experiment, _________ and ___________ should be kept unchanged and the ______ of the object should be changed.

② Observe the readings of the spring dynamometer when different objects of the same volume are weighed in the air and immersed in the same liquid. If the readings are the same, it means that the buoyancy force has nothing to do with the density of the object, and vice versa. .

Experiment 2: Explore the relationship between the buoyancy force and the gravity of the displaced liquid

(1) Experimental device: As shown in Figure 10-T-5.

(2)Experimental design

① Use diagram A to measure the ____ force exerted on an object.

②The indication of the spring dynamometer in Figure B is ____ (optional "larger" or "smaller") than the indication of the spring dynamometer in Figure A. The difference between the two indications is the buoyancy force on the object. .

③The difference between the spring dynamometer readings in Figure C and Figure D is the gravity force on the displaced liquid.

④ Comparing the buoyancy force with the gravity exerted by the object displacing the liquid, we can draw the conclusion: _______________________________________________.

(3) Experimental plan evaluation

① If the water in the overflow cup is not full, it will cause the F measured in this experiment to float _____ (optional ">" or "<") G row.

②After the experiment, the teacher reminded the students to conduct another experiment using other objects. The meaning of this operation is ____________________.

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Update Time: 2024-07-31

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