First physics experiment report
"Buoyancy disappeared" to do the following small test.
Look for a container with a flat bottom, let a candle head cling to the bottom of the container, pour water into the container, the candle head will not float; gently lower the candle head, it will immediately float.
It can be seen that when the object is in close contact with the bottom of the container, there is no liquid infiltration between the two contact faces, and the lower surface of the object is no longer pressed by the liquid against it, and the liquid loses the upward force on the liquid, and the buoyancy is of course followed. Disappeared.
Now, can you propose measures to get rid of the submarine?
"How buoyancy is produced", the student's conclusion that "buoyancy is the difference between the pressure of the liquid on the object and the downward pressure" is understandable, but it is hard to believe, so the experiment of buoyancy disappearing is to overcome this. The key to a difficult point is the following two simple methods.
[method 1]
Equipment: One glass funnel of appropriate size, one billiard, one cup of red water.
step:
The billiard is intentionally dropped into the water, and the table tennis ball floats quickly after the hand is released.
Hold the funnel with your hand, put the billiard ball in it, hold the billiard ball with your thumb, pour the water into the funnel, and release the thumb, so that the billiard ball does not float.
Block the water outlet with your fingers, and the water level in the funnel handle gradually rises. When the water surface rises to the billiard, the table tennis ball rises quickly.
[Method 2]
Equipment: one transparent flat plastic bucket, one wooden block with a flat bottom, one chopstick, one cup of water.
Make a small hole barrel: Take a shovel to burn red on the alcohol lamp, wear a small hole in the center of the bottom surface of the plastic barrel, and the hole diameter is about 1cm. Use sandpaper to smooth the hole edge to form a small hole barrel.
step:
The wooden block is intentionally dropped into the water, and the wooden block quickly floats after the hand is released.
Place the flat side of the wooden block down into the small hole barrel and cover the small hole. Hold the wooden block with chopsticks and pour the water into the barrel. Remove the chopsticks and notice that the wooden blocks do not float. . The article you are browsing is organized by the first 'Panwen.com', and the copyright belongs to the original author and the original source.
Block the small hole with your fingers and the wooden block will float immediately.
The above two cases are aimed at the fact that the surface of the actual object cannot be absolutely smooth, and the "small hole leakage" is skillfully utilized so that the water does not remain under the object, so that the object loses the upward pressure of the liquid, and the buoyancy is lost. The billiards and wooden blocks that should have floated on the water were firmly nailed to the bottom of the water, and the students could not help but admire them. Then the steps magically reproduce the buoyancy, and the students are more emotional and eager to try.
Students observe problems and solve problems themselves.
Look for a container with a flat bottom, let a candle head cling to the bottom of the container, pour water into the container, the candle head will not float; gently lower the candle head, it will immediately float.
It can be seen that when the object is in close contact with the bottom of the container, there is no liquid infiltration between the two contact faces, and the lower surface of the object is no longer pressed by the liquid against it, and the liquid loses the upward force on the liquid, and the buoyancy is of course followed. Disappeared.
Now, can you propose measures to get rid of the submarine?
"How buoyancy is produced", the student's conclusion that "buoyancy is the difference between the pressure of the liquid on the object and the downward pressure" is understandable, but it is hard to believe, so the experiment of buoyancy disappearing is to overcome this. The key to a difficult point is the following two simple methods.
[method 1]
Equipment: One glass funnel of appropriate size, one billiard, one cup of red water.
step:
The billiard is intentionally dropped into the water, and the table tennis ball floats quickly after the hand is released.
Hold the funnel with your hand, put the billiard ball in it, hold the billiard ball with your thumb, pour the water into the funnel, and release the thumb, so that the billiard ball does not float.
Block the water outlet with your fingers, and the water level in the funnel handle gradually rises. When the water surface rises to the billiard, the table tennis ball rises quickly.
[Method 2]
Equipment: one transparent flat plastic bucket, one wooden block with a flat bottom, one chopstick, one cup of water.
Make a small hole barrel: Take a shovel to burn red on the alcohol lamp, wear a small hole in the center of the bottom surface of the plastic barrel, and the hole diameter is about 1cm. Use sandpaper to smooth the hole edge to form a small hole barrel.
step:
The wooden block is intentionally dropped into the water, and the wooden block quickly floats after the hand is released.
Place the flat side of the wooden block down into the small hole barrel and cover the small hole. Hold the wooden block with chopsticks and pour the water into the barrel. Remove the chopsticks and notice that the wooden blocks do not float. . The article you are browsing is organized by the first 'Panwen.com', and the copyright belongs to the original author and the original source.
Block the small hole with your fingers and the wooden block will float immediately.
The above two cases are aimed at the fact that the surface of the actual object cannot be absolutely smooth, and the "small hole leakage" is skillfully utilized so that the water does not remain under the object, so that the object loses the upward pressure of the liquid, and the buoyancy is lost. The billiards and wooden blocks that should have floated on the water were firmly nailed to the bottom of the water, and the students could not help but admire them. Then the steps magically reproduce the buoyancy, and the students are more emotional and eager to try.
Students observe problems and solve problems themselves.
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