Analytical syringes are no strangers to us. If you can use your brain and make use of its characteristics of "piston can pull" and "seal a part of gas", you can do many experiments.

(1) Block the front hole with your finger and pull the piston outward with your other hand. It's hard to touch your hands. If the push is stopped, the piston will retreat a certain distance, which verifies the existence of atmospheric pressure.

② Take a syringe, push the piston to the bottom, block the small hole at the front end with your fingers, and pull the piston to the middle of the pipe. At this time, the finger blocking the small hole will be immersed in water, and water will enter the syringe, which verifies the principle of the water pump-working at atmospheric pressure.

In addition, the injector can also demonstrate the method of gas liquefaction, verify the relationship between gas pressure and volume, and demonstrate the relationship between gas pressure and liquid boiling point. Have you figured out what to do?

Example 2 Give you a long sharpened pencil, please use it to design two small physics experiments.

This is a good experimental problem to cultivate observation ability, experimental ability and innovation ability. Pencils are also commonly used stationery, so experiments are easy to carry out.

① Press both ends of the pencil with index finger and thumb respectively, and the indentation depth of fingers is different, indicating that "the pressure is related to the stress area"; Fingers will feel pain when pressing a pencil, indicating that "the action of force is mutual"

② Wrap a thin wire around one end of the pencil or press it into one end with a thumbtack to make it float vertically in water and other liquids. According to the depth of immersion in liquid, the density of liquid can be judged.

③ Wrap the thin wire tightly around the round pencil, and then measure the total length d of N turns of copper wire with a ruler to get the diameter of the wire.

In addition, it can also be considered from the aspects of light, heat and electricity. For example, if a pencil stands straight on the ground in the sun or light, the shadow of the pencil will appear, indicating that "light travels in a straight line in the same homogeneous substance"; Heat one end of pencil lead with an alcohol lamp, and the other end of pencil lead will heat up after a while, indicating that "pencil lead is a good conductor of heat"; Connecting one end of the lead wire with one end of the lead core and sliding the other end on the pencil lead changed the length of the pencil lead connecting the circuit, and found that the brightness of the bulb changed. This experiment can explain the principle of sliding rheostat.