1. manufacturing: take a jar, cut off the upper part, cover it with a translucent film, and make a small hole in the bottom (as shown in the figure) to demonstrate the imaging of the small hole.
2. Deep exploration
(1) Image size change: changing the distance from the candle to the hole, the experiment found that "when the candle is close to the hole, the image of the candle flame becomes larger, and when the candle flame is far away from the hole, the image becomes smaller"; You can also combine two cans so that you can stretch them. During the experiment, keep the candle still and change the distance from the translucent film to the hole. It is found that the image of candle flame becomes smaller when the can is shrunk, but it becomes larger when the can is elongated. It shows that the size of pinhole imaging is related to the distance between candle and pinhole and the distance between translucent film and pinhole, and the image can be enlarged, reduced or the same size.
⑵ Influence of pinhole size on image: In the experiment, the pinhole size changed from small to large, while keeping the distance from candle and translucent film to pinhole unchanged. It is found that "the larger the pinhole, the less clear the image, and finally only one light spot can be obtained, so the pinhole imaging is" small enough ",and the pinhole size affects the imaging clarity.
⑶ Influence of pinhole shape on imaging: Pinholes can be made into various shapes, such as circles, triangles, squares, etc. It is found in the experiment that the formed image has nothing to do with the pinhole shape.
Second, demonstrate the existence of atmospheric pressure.
As shown in the figure, put a small amount of water in an aluminum can and heat it with an alcohol lamp. When there is white fog at the jar mouth, block the jar mouth with plasticine (or dough), remove the alcohol lamp and let the jar cool naturally. It is found that "the cans are crushed" means "the existence of atmospheric pressure", and it can also explain "the force can change the shape of objects" and "the relationship between atmospheric pressure and temperature-the temperature decreases and the pressure decreases".
Third, explore buoyancy.
(1) Experience the existence and change of buoyancy: put half a bucket of water in the bucket. When you press an empty can into the water by hand, you will feel the upward thrust of the can. The deeper you press it, the greater the thrust on your hand (the greater or more laborious the downward pressure of your hand), and you will feel the existence and change of buoyancy (the greater the volume of discharged liquid, the greater the buoyancy).
⑵ Demonstrate the ups and downs of an object: take a jar, cut it off, the lower part is slightly smaller and keep the shape of the container (the upper part is cut into a rectangle), put it in a sink, it can float on the water, and the upper part sinks to the bottom.
⑶ Explore the floating conditions of the object: Explore the floating conditions of the object by using the made lower part and suitable counterweight (small nuts, nails, sand, etc.). ). Measure the gravity of the lower part and the counterweight with a spring dynamometer, then hang it on the spring dynamometer and put it into the water. When it floats, it is found that the pointer of the spring dynamometer becomes zero, which leads to the conclusion that "when the object floats, F floats = G".
Fourth, show the transformation of energy.
As shown in the figure, tie a small iron block in the middle of the rubber band, let the rubber band pass through the tank body, and both ends are fixed on the tank cover and tank bottom respectively. After the completion of the experimental device, let it roll down a slope that is not too steep, and find that the rubber band is tightly wound by iron blocks, and then tin can automatically roll up from the bottom of the slope! "The cans roll from the bottom to the lowest place on the inclined plane, mainly because the gravitational potential energy is converted into elastic potential energy, and the cans roll from the lowest place to everywhere on the inclined plane, mainly because the elastic potential energy is converted into gravitational potential energy".