I m going to ask for the second year of junior high school physics questions again

Wrong. The temperature does not necessarily increase after the object absorbs heat. When there is a change in the state of an object.

For example, when dissolving from a solid state to a liquid state, a large amount of heat is absorbed, but the temperature does not change. The heat energy absorbed at this time is used to overcome the energy required for lattice disruption between solid molecules. When the liquid turns into gas.

It's when it boils and gasifies. Again, it is necessary to absorb a lot of heat. This energy is used to overcome the molecular forces between the liquids.

Generally speaking. If there is no change in the state of the object. It is still right to absorb heat and raise the temperature.

It must be true, because the temperature of an object itself is constant, such as; When a piece of ice is placed in the air, when the temperature of the air is 20 degrees Celsius, the ice will naturally melt after a certain period of time, which means that the temperature of the ice rises after absorbing external heat in the process

Not exactly, because for example, sea waves, ice and various metals. They are called crystals despite the constant heat absorption during the melting process, but the temperature remains the same. Of course, there are also examples of vaporization processes and sublimation processes.

Some amorphous wax, rosin, glass, etc., in the melting process, as long as the heat is constantly absorbed, the temperature will continue to rise, and there is no fixed melting temperature. Of course, there are also examples of liquefaction and condensation processes.

Obviously not. Counter-example: In the process of changing from zero-degree ice to zero-degree water, it continuously absorbs heat, but the temperature does not change.

Because the heat is converted into the molecular potential energy of the internal energy, without increasing the temperature. In short, the absorption of heat is equal to the change of internal energy (divided into molecular potential energy and molecular kinetic energy, molecular kinetic energy is reflected in temperature, and potential energy is more complex) and external work.

Absolutely, not to find me

Wrong. The temperature of the crystal remains constant at the melting point during the melting process and neither rises nor decreases.

Wrong. When the object is boiling, melting, solidifying, the temperature does not change.

Wrong. Liquids generally have a melting point and a boiling point, and in both cases, the object will only give off or absorb heat, but the temperature will not change! ~

I don't think so, because crystals melt or solidify to reach a certain melting point or freezing point, and the temperature does not change no matter how heated they are.

The question in this question is melting, and based on the above, it can be seen that this question is incorrect.

Not true. If the object is a crystal, it absorbs heat during melting, vaporization, and sublimation, but the temperature does not change.

No, when the crystals are boiling, the temperature does not rise, but they continue to absorb heat.

Wrong. When water is boiling; when water evaporates; when the ice melts; when ice vaporizes;

The temperature is the same.

Wrong. If the object being heated reaches the boiling point or melting point.

Although it will absorb heat.

But the temperature will remain the same.

It's called.

Solid-liquid coexistence.

Not true. Why. Forgot what to say--

When the object melts, the crystals begin to absorb heat, prepare to melt, and when they reach the melting point, they begin to melt (i.e., from a solid to a liquid), at which point the temperature remains the same despite endothermic receptivity, and the temperature does not rise until it has melted (i.e., it has completely become liquid).

Wrong. If it melts, it absorbs heat and the temperature does not change.

No, although the crystals absorb heat during the melting process, the temperature does not change.

（1）27km/s=

270m<500m

Able to catch up with thieves within 500m.

2）27km/s=

The police caught up with the thief and walked a total of 270m.

27km/h=

Known: s = s police - thief 90 m v thief = 5m s v police =

Find: s=vt s distance.

Solution: s=vt

270m<500m

Answer: 1) Yes;

2) Gone.

I hope the landlord can do it himself, I'll give you some hints, so that you can make this catch your own, otherwise it's still mine, you have to master it yourself!

The landlord converted the police 27km h into m s and then did it with mathematical equations.

27km is 90 ( so can, the distance is 270 meters.

1.Overloaded trucks will seriously damage highway facilities and pose a serious threat to the safety of highway bridges. Please apply what you have learned to explain the cause of damage to the bridge pavement caused by severely overloaded trucks.

Answer: According to the pressure formula p is equal to f divided by s (pressure is equal to pressure divided by the force area), under the condition that the force area s is constant, the overloaded transportation of the truck increases the pressure f, thereby increasing the pressure p on the bridge deck, so the seriously overloaded truck damages the bridge deck.

On February 2, I counted the first 1,000-ton special maritime surveillance ship for rights protection and law enforcement, "China Maritime Surveillance 8002", which was officially listed, with a mass of 1337t when fully loaded, a maximum speed of 37 kilometers per hour, and a cruising capacity of 5,000 nautical miles, which is currently the largest and most advanced law enforcement equipment in Fujian maritime surveillance ships. Question: (1) When it is fully loaded and stationary on the sea, what is the buoyancy experience?

2) When the maritime surveillance vessel is stationary on the surface of the sea, if the depth of a part of the ship hall is two meters from the sea surface, what is the pressure of the seawater at that place? (Pressure of seawater = A: Known:

m = 1337t = 1337000kg, density of seawater = 1030kg m 3, g = 10n kg, h = 2m.

Find: (1) f float, (2) pressure p

Solution: (1) Obtained by g=mg.

G ship = 1337000kg * 10N kg

13370000n

Because the ship is stationary on the surface of the sea, that is, floating.

So f float = g ship = 13370000n

2) It is obtained from p = density of the liquid * g * h.

p=1030kg/m^3*10n/kg*2m

20600pa

A......3.An athlete won a gold medal in the women's weightlifting over 75kg category at an international event, with a clean and jerk of 165kg. Some athletes are about meters tall, can you estimate how much work he has done on the bar bell during the clean and jerk?

Answer: It is known that m=165kg, g=10n kg, s=h=

Solution: w: obtained from g=mg.

g=mg=165kg*10n/kg=1650n

Because f=g=1650n

So it is obtained by w=fs.

w=fs=1650n*

A......4.If someone uses a force of 100N to press down the end of the lever power arm by 2m in the vertical direction, and the other end of the lever is lifted with a weight of 320N, what is the useful work he has done? What is the mechanical efficiency of a lever?

Answer: Known: f=100n, s=2m, g=320n, h=

Seeking: w has (useful work), mechanical efficiency.

Solution: obtained by w=fs.

w has =gh=320n*

W total (chief engineer) = FS = 100N * 2m = 200J

It is obtained by mechanical efficiency = (w has w total)*100%.

Mechanical efficiency of the lever = w has w total * 100% = 160j 200j * 100% = 80% A......

4 16, the hand will feel pain when the person taps the table with the hand, because the force is the effect of the force, the person pulls the spring, and the pulling force makes the spring happen The goalkeeper kicks back the ball that flies towards the goal, assuming that the speed of the ball comes and goes is the same, and the force of the kicking ball changes the motion of the football 17. When the car starts suddenly, because the passenger has He will dump; When a car heading north suddenly turns westward, the passengers in the car will tip over. 18. Bingbing holds a water cup weighing 10N with his hand and is stationary in the air, the mouth of the cup is vertically upward, and the grip of the hand is 20N, then the friction of the water cup is N; If the grip strength of the hand is increased to 30N, the friction force experienced by the water cup is n.

19, put a brick flat, vertically, sideways on the horizontal ground, the least pressure on the ground in the three ways is put, the greatest pressure on the ground is put. 20. The "Olympic Torch Climbing Mount Everest" created a historical precedent for the Olympic torch relay. The torch marched to Mount Everest, "altitude sickness" is one of the many difficulties that the team members must face, "altitude sickness" is related to air pressure, the higher the altitude, the greater the atmospheric pressure optional "bigger" or "smaller"); The reason why you can't cook rice in an ordinary pot on the plateau is because the boiling point of the water is 100 when you cook it in an ordinary pot.

The density of copper is greater than that of iron.

So: a, c, d

d The volume ratio of the solid part of the iron ball to the copper ball is 89:79

1. Home circuit connection method: the parallel relationship between each lamp, electrical appliance and socket; The switch is connected in series with the light.

2. The main part of the home circuit:

1) The line with a voltage of 220 volts with the earth is called the live wire, and the line with the earth without voltage is called the zero line.

2) The function of the electric energy meter: to measure the electric energy consumed by all the electrical appliances of the user.

3) Two characteristics of the material of the fuse: resistance (rate) large melting point low lead-antimony alloy).

3. Safe use of electricity: Electric shock accidents in household circuits are caused by people directly or indirectly communicating with or constructing paths with live wires. For safety, do not touch low-voltage charged bodies, and do not approach high-voltage charged bodies.

Back to the sophomore classmate: the resistance must be large, because no matter how large the fuse resistance is, it will not say that the voltage division is very large, and it may divide a little voltage, but it will not affect the use of electrical appliances.

The reason why we don't use copper wire as a fuse is because the copper wire has a small resistance and a small partial voltage, and then it can't achieve the role of insurance, so we use a lead alloy with a high resistivity.

1, and skewers.

2 (1) Fire Zero.

2) Electric work. 3) Big Low.

3 people fire earth.

Touch closer.

1. Parallel; Concatenation.

2, (1) live line; Zero line.

2) Electrical energy. 3) Large; Low.

3, human body; Fireline ; Zero line. Touch; Near.

Uh, I'm sorry, I studied mechanics in my first year of high school, and I forgot.

1. Parallel; Concatenation.

2, (1) live line; Zero line.

2) Electrical energy. 3) small; Low.

3, human body; Fireline ; Zero line. Touch; Near.