A simple physics problem! A physics problem!

Gravity is not equal to the gravitational pull of the Earth on an object. Due to the rotation of the earth itself, in addition to the poles, the objects in other places on the ground are moving in an approximate uniform circular motion around the earth's axis together with the earth, which requires a centripetal force directed perpendicularly to the earth's axis, and this centripetal force can only be provided by the earth's gravitational force on the object, and we can decompose the earth's gravitational force on the object into two components, one component f1, which points to the earth's axis, and the magnitude is equal to the centripetal force required for the object to move in an approximate uniform circular motion around the earth's axis; The other component g is the gravitational force on the object, where f1 = mw2r (w is the angular velocity of the earth's rotation and r is the radius of rotation of the object), and it can be seen that the magnitude of f1 is zero at the poles, increasing with the decrease of latitude, and the maximum f1max is in the equatorial region. Because the centripetal force of the object is very small, in general, it can be approximated that the gravitational force of the object is equal to the gravitational force, that is, the influence of the rotation of the earth can be omitted in general.

where the gravitational component of gravity provides gravitational acceleration and the centripetal component of gravity provides centripetal acceleration that maintains rotation with the earth.

Not equal! Strictly speaking, gravity is the combined force of gravity and centripetal force hehe.

Hehe, not equally.

Gravity is the vertical component of the guiding force, and gravity is not perpendicular downward and has an angular difference.

Upstairs, don't talk nonsense if you don't understand what centripetal force is

Gravitational force is the gravitational force, which decomposes into two directions, the component force in one direction is the centripetal force when it rotates with the earth, and the component force in the other direction is the gravitational force.

Acceleration upwards is overweight.

Iron with a mass of 1 kilogram, resting is a Newton weight. How much would it weigh if it was allowed to fall freely from the upper floors before it finally hit the ground?

One theory is that it is still this piece of iron, and its position has not changed, and it has not gone up from high latitudes to the equator, so the weight remains the same, and it still weighs Newton. Another way to put it is:

Whatever the object, at the time of free fall, its weight should be equal to zero. So iron with a mass of 1 kg, at the time of free fall, its weight is equal to zero.

Who is right and who is wrong with these two opposing statements?

This is indeed a very interesting question for travelers, and what is the rationale for these two statements?

The reason for the first statement is that the weight of an object is caused by the attraction of the earth to the object, which is approximately equal to the force of the earth to attract the object, so the weight is also called gravity, and the unit is the same as the buried unit of the general force. The earth is as attractive to stationary objects as it is to moving objects, but is it not attractive to free-falling objects?

If an object is not attracted to the Earth, it will not fall at all, how can it be said that its gravity is equal to zero? Therefore, no matter how the object moves, its weight should always be the same as when it was at rest, and it will not change much, let alone equal to zero.

The second argument is that the weight of an object should be determined by the result of the measurement. You will feel pressure when you hold an object by hand, and you will feel a pull when you hold an object by hand; In daily life, we all judge the weight of an object by the amount of pressure or tension.

Measuring the weight of an object with a spring scale is, of course, much more accurate than estimating it by hand, but the truth is that the weight is measured by the pressure or tension of the object on the spring. Put a piece of iron in the palm of your hand, let it stand still first, and try its weight; Then raise your hand sharply to move the iron upwards, and you will definitely feel that it is much heavier than it was at rest, and then you will feel that it is much lighter again than when you were at rest. If you do the same experiment by holding a spring scale with an iron block hanging from it, you can see the increase or decrease in weight more clearly.

In this way, both claims make sense. It is true that the weight of the object is generated by the gravitational pull of the earth, and it does not change with whether or how the object moves, but only with the position of the object. In this case, we call it "solid weight".

As for the weight weighed with a spring scale, it should be called "apparent weight".

At rest, the "apparent weight" of the object is exactly equal to the "real weight", but when in motion, the "apparent weight" of the object can be greater than, less than, or equal to the "real weight", depending on the motion. When an object is in free fall, its "apparent weight" is indeed equal to zero.

"Apparent weight" greater than "real weight" is called "overweight", and "apparent weight" less than "actual weight" is called "weightless".

I hope I can help you with your doubts.

1. The liquid pressure is related to the density and depth of the liquid (P= GH), and has nothing to do with the shape and bottom area of the container.

The density and depth are equal, so the pressure is equal.

2. f=ps. The pressure is equal, the bottom surface is equal, and the pressure is equal.

1.The pressure is just as great. Because pressure = density of liquid * height, the height is equal, so the pressure is equal.

2. The pressure is also equal, because the magnitude of the pressure = gravity.

I want to ask you if there is anything wrong with the question, is the high equal?

1) W total = GH = MGH = 120 10 10 20 =, W has = W total = generator amount power p = W has t =

2) The work done in 5s w has = p total t =, the weight g = w has the work done in h30s.

The high selling collapse of the 30s crane with the liter to do the work of Qi Yuan, p has = p total =, the work done by the crane w has = p has t =, 3) the current of normal operation.

i = u r lamp = 12 20 =, resistor voltage u2 = u-u1 = 16-12 = 4v, resistance.

r=u2/i=4/

The content of the law: The acceleration of an object is proportional to the resultant force f exerted on the object, inversely proportional to the mass of the object, and the direction of acceleration is the same as the direction of the resultant external force.

2 Formula: f = ma

3 A few notes:

1) Newton's second law is the law of instantaneous action of force. Force and acceleration are generated, changed and dissipated at the same time.

2) f=ma is a vector equation, the positive direction should be specified when applying, all the force or acceleration with the positive direction is taken positive value, vice versa is taken negative value, generally often take the direction of acceleration in the opposite direction.

3) According to the principle of independent action of forces, when Newton's second law is used to deal with the problem of the motion of an object in a plane, the forces subjected to the object can be orthogonally decomposed, and the component form of Newton's second law can be applied in two mutually perpendicular directions: fx=max, fy=may.

4.The five properties of Newton's second law:

1) Homogeneity: F, M, and A correspond to the same object.

2) Vectorability: Force and acceleration are both vector quantities, and the direction of acceleration of the object is determined by the direction of the combined external force on the object. In the mathematical expression of Newton's second law f = ma, the equal sign not only indicates that the left and right sides are equal in value, but also indicates that the direction is the same, that is, the direction of the acceleration of the object is the same as the direction of the combined external force.

3) Transientness: When the external force on the object (with a certain mass) changes suddenly, the magnitude and direction of the acceleration determined by the force should also change abruptly at the same time; When the resultant external force is zero, the acceleration is zero at the same time, and the acceleration and the resultant external force maintain a one-to-one correspondence. Newton's second law is an instantaneous law that indicates the instantaneous effect of force.

4) Relativity: There is a coordinate system in nature, in which the object will maintain a uniform linear motion or a stationary state when it is not subjected to force, and such a coordinate system is called an inertial reference system. The ground and objects that are stationary or moving in a straight line at a uniform speed relative to the ground can be regarded as inertial frames of reference, and Newton's laws are only true in inertial frames of reference.

5) Independence: Each force acting on the object can independently produce an acceleration, and the sum of the acceleration generated by each force is equal to the acceleration generated by the combined external force.

The scope of application of Newton's second law.

1) This paragraph is only applicable to objects moving at low speeds (lower velocity than the speed of light).

2) It only applies to macroscopic objects, Newton's second law does not apply to microscopic atoms.

3) The frame of reference should be an inertial frame. 27

1 The principle of superposition refers to the overall effect at the time of encounter.

Potassium chlorate - manganese dioxide, heating potassium chloride + oxygen.

2kclo3 = mno2 2kcl + 3o2 1, oxygen is poorly soluble in water, but there is still a small part that can be dissolved in water.

2. Oxygen can be used to supply breathing.

1.The pencil refills of the Zen pencils are placed next to each other in turn and laid flat on the table.

2.Use a scale circle to measure the total length of n pencil leads, L

3.then the diameter of a single pencil lead is d=l n

4. Repeat three times to take the average.

I don't know what the current learning situation of junior high school students is, but after reading your questions, I think you have forgotten that Li Haihong has lost his original intention of life, and studying is for a better life, not to cope with exams;

This question itself is quite interesting, let me ask you, which book of moving pencil refills do you use, and there are two kinds of general, right? Take one and compare it on the scale, have you ever seen a refill?

It is possible to line up 10 refills together for measurement. After that, put the total length of 10 on it.

If you put x refills side by side, the diameter is xd xd x d = 1mm, then d = 1 mm of x

Problem 1: The time taken for the vertical throwing process t1=5 10=1 2s rise height h1=v squared (2g)=

So the total height of the fall is h=h1+h2=

so t2=

Question 2: You wait a minute, I'm doing it, and I'll give it to you.

1.Solution: obtained by v=at1.

t1 = The time it takes for the iron ball to fall from 30 meters is t

vt+t=2s

t2=t1+t=

Iron ball rise time, fall time.

2.Solution: (1) It is obtained by the kinetic energy theorem.

0-mv 2 2=-(mgxsina + umgx) gives x=

2) From Newton's second law.

mgsina-umgcosa=ma

The solution gives a= from x=at2 2 and t=