Give some physics questions in the second year of junior high school, and physics questions in the s

1.It's called sublimation, and sublimation is filling"Suction"or"put"Thermal process.

Idea analysis: Under the condition of satisfying certain conditions, a substance can directly change from a solid state to a gaseous state without going through a liquid state, and this change process is called sublimation, and sublimation is an endothermic process.

Answer: The substance changes directly from a solid state to a gaseous absorption.

2.Put mothballs in the closet to prevent insects, and finally the mothballs become smaller, this is a phenomenon, and in this process of change it is hot.

Idea analysis:"Mothballs have become smaller"It is the solid mothballs that turn into gaseous camphor and emit into the air, which is a sublimation phenomenon.

Answer: Sublimation sucks.

3.It's called coagulation, and coagulation is a thermal process; It's called liquefaction, and liquefaction is a thermal process; It's called condensation, and condensation is a thermal process.

Analysis: The exothermic process in the change of state of matter includes solidification, liquefaction and condensation, and the key to accurately understanding the concepts of these three kinds of state change is to be able to accurately distinguish them from melting, vaporization and sublimation.

Answer: The substance changes from a liquid state to a solid state, and the substance changes from a gaseous state to a liquid state, and the substance is released from a gaseous state directly to a solid state.

4.Fill in the names of the changes in the state of matter for the following phenomena: Spring flowers bloom, snow and ice melt Summer is scorching, and the water sprinkled on the ground disappears for a while Winter snow falls

Answer: Melting vaporization (evaporation) condensation.

10-minute training session (intensive training, can be used during the session).

1.The melting point of tungsten is 3410, so which of the following states is tungsten in at 3410 ().

a.Solid state BLiquid CSolid-liquid coexistence state dAll three of the above are possible.

Analysis: If the solid tungsten temperature reaches 3410, it cannot absorb heat from the surroundings, then the tungsten is still in the solid state; If it can absorb heat from the surroundings when it reaches 3410, the tungsten will melt and be in a solid-liquid coexistence state; When the tungsten is melted just after it is melted, it no longer continues to absorb heat, and the tungsten is in a liquid state at this time.

The direction of the propeller discharge should be against the current, that is, opposite to the direction of the current. This counteracts the force of the ocean current on the column and maintains the balance of the column.

Assuming that the direction of the current is from left to right, then the force of the current on the column is to the right. To counteract this force, the propeller has to drain water to the left, i.e. against the direction of the current. In this way, the reaction force generated by the displacement of the propeller can be equal to but opposite to the force of the ocean current, so that the resultant force on the column is zero and the balance is maintained.

Common types of questions in physics include force calculations, simple circuit diagrams, and fluctuating sound (light). The question type of computation is generally based on Newton's question.

The application of related concepts such as the one, two, and three laws and the resultant force, and the simple circuit diagram is calculated by applying basic concepts such as Ohm's law. For the fluctuation question, you need to understand the basic formulas of fluctuation, such as wavelength, wave velocity and frequency. When doing the questions, you need to pay attention to the requirements of the questions, pay attention to the units and symbols of the data, and do not be hasty and hasty.

Through repeated practice and consolidation of the basic knowledge and calculation methods of physics courses, the performance and level of physics learning can be effectively improved.

The study of physics in the second year of junior high school mainly includes mechanics, optics, heat, electricity, etc. In mechanics, students learn about the laws of motion of objects, Newton's three laws, and the synthesis and decomposition of forces. In optics, students will learn the definition of light, the propagation, reflection, and refraction of light.

In thermal, students learn about temperature, heat, heat transfer, and thermal expansion. In terms of electricity, students will learn the principles, circuit basics, capacitors, resistors, inductors and other common electrical components. In the second year of junior high school physics learning, a lot of observation and practice, theory and practice are required to cultivate students' hands-on ability and ability to solve practical problems, such as measuring experiments, designing experiments, etc.

Physics is a basic science, which is of great significance for cultivating students' scientific literacy.

The main learning content of Physics in the second year of junior high school includes the basic concepts of physics, kinematics, mechanics, energy conversion and mechanical waves. Studying physics can enable students to better understand the laws of nature and improve their thinking skills and scientific literacy when solving practical problems. For example, studying kinematics can help us better design the training of athletes in order to understand the trajectory and velocity changes of objects in space

See the figure below for details, click to enlarge:

First of all, mass = volume x density.

1. The mass is the same, the density of A is 2 times that of B, then the volume of A is 1 2 of B;

2. The volume is the same, the density of A is twice that of B, and the mass of A is also twice that of B.

These two questions are the same thing, mass m = v

From the formula, m is equal, the density and volume are inversely proportional, the density is large, the volume is small, the density is several times larger, the volume is several times smaller.

The volume is equal, the density is proportional to the mass, and the density is several times larger, and the mass is several times larger. ，

The spring dynamometer reads equal to the force at the hook, and since the hook is being held in the diagram, the force at the hook is exactly equal to the gravitational force of the spring dynamometer.

B dynamometer is used upside down, the spring bears both its own weight and the weight of the cow hook yard, and the spring dynamometer has a self-weight of 1 New, so the B dynamometer indicates that the number is Ox.

A dynamometer is used normally, its own weight is borne by the iron frame, the spring of a dynamometer bears the weight of B dynamometer and the weight of two ox hook yards, so a dynamometer shows 1 ox + cow + cow = 2 n. So choose C

A dynamometer is used normally, therefore, there is no problem with the reading of a nail dynamometer.

B The dynamometer is used upside down, so that it will appear, and when there is no object hanging on the pull ring, the dynamometer will also have an indication. This indication is the gravitational force of the dynamometer itself.

1. Linear propagation Shadow Linear propagation of light 2. d Walk from a distance to the lamp and become shorter, and then leave and become longer3. The moon blocks part of the sun's rays Moving around the sun4. A This question examines the problem of imaging small holes, what is the shape of the object, and what is the shape of the image5, (1) Make the straw into a straight shape, illuminate it with a laser pointer at one end, if the light of the laser pointer shoots out from the other end, it proves that the light travels in a straight line in the air.

2) Bend the straw and shine it with a laser pointer at one end, if the light of the laser pointer cannot be shot from the other end, it proves that the light cannot travel along the curve in the air.

1.Straight line propagation Shadow Light travels in a straight line, blocking part of the sun's light movement (aperture imaging).

5.(1) Straighten the straw and pass the light of the laser pointer through the straw.

2) Bend the straw so that light can't pass through.

Light travels in a straight line, shadows, light travels in a straight line.

d. Linear propagation of light, motion b

1.Straight line propagation Shadow Straight line propagation of light 2 d 3 The Moon is in the middle of the Earth and the Sun Motion 4 a 5

o Ice water mixture at degrees Celsius, water does not evaporate because it does not absorb heat.

2.B should be cooked over a simmer. d

3.No change. The sweat on Xiaohong's face vaporizes and absorbs heat, so it feels cool. But the cold and summer table is room temperature. So it doesn't change.

D At 0 degrees, there are 6 variations of sublimation liquefaction and so on.

d After boiling, the temperature remains the same, no matter how big the fire is, the heat transfer is also about the same.

Elevation Turn on the electric fan, the electrical energy is converted into mechanical energy and eventually into heat energy, so the temperature rises.

d, c unchanged. Reason: The electric fan accelerates the flow of air around Xiaohong, and the sweat on Xiaohong's body is accelerated by the wind and evaporates, absorbing heat, so she feels cool. The electric fan does not cool, so the temperature of the cold and summer meters does not change.

3.raised, because in the process of fanning the fan, Xiao Ming's own heat was quickly released into the air in the room.