Small Ideas in Physics 20, Small Ideas in Physics

Is the landlord a junior high school student or a high school student?

1.In junior high school, it was believed that gravity must be directed towards the center of the earth.

High school level: gravity points to the center of the earth, and a global object can be considered equal to gravity, at which point to the center of the earth.

For objects on the ground, the gravitational force is divided into the centripetal force and the gravitational force used by the earth to rotate. The centripetal force is directed towards the earth's axis, so the gravitational force is not directed towards the center of the earth (deviates a little).

But for objects on the equator, gravitational force, gravity, and centripetal force are in the same direction, and pointing to the earth's axis on the equator is pointing to the center of the earth;

Objects at the poles, do not need centripetal force, gravitational force all provides gravity, and at this time also points to the center of the earth.

2.It is true that the earth is not a regular sphere, and through modern observation methods, it has been confirmed that the diameter of the earth's equator and the length of the earth's axis are not equal, so it is naturally not a circle. In fact, the earth is shaped like a pear:

Its equatorial part is bulging, and it is its "pear body"; The North Pole is a bit pointed, like a "pear"; The South Pole is a bit concave, like a "pear navel", and the whole earth resembles a pear-shaped rotating body, so people call it "pear-shaped Earth".

3.Surface objects can be thrown off in addition to being attracted. The first thing to understand is what is"Shake it off", that is, the object is on the surface of the planet"Gone with the Wind", no longer in contact with the planet, the critical condition is that gravity completely provides the centripetal force.

If you don't understand, you can continue to ask.

What you mean by "sucking" is actually the force of gravity after subtracting the centripetal force from the vector? This force is gravity, when the gravitational force is large enough to meet the centripetal force required for the object to move in a circle, and the radius of motion is the radius of the planet, at this time the gravitational force is just enough for the centripetal force, so the object does not squeeze the planet, and there is no gravity, and moves with the planet, relative to the planet stationary.

If the gravitational force is too small to meet the centripetal force required for the object to move in a circular motion on the surface of the planet, then the radius of motion of the object becomes larger, that is, it moves in a circular motion over the planet, and there is no gravity at this time.

If the gravitational force is too large, while satisfying the centripetal force required for the object to move in a circular motion on the surface of the planet, the "left" force is what we usually call gravity, which is a component of gravity, that is, the vector sum of the gravitational force and the centripetal force on the object is equal to the gravitational force. Moreover, at the pole and the equator, the direction of the centripetal force, the direction of gravity and the direction of gravity are the same, then gravity is not a component force, but the force obtained by subtracting the centripetal force from the gravitational force.

I don't quite understand what you're asking, "Can't a sphere attract an object to its surface and rotate with it?"

Please be clear. <>

The direction of gravity is exaggerated.

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The combined force of gravity and centrifugal force is gravitational and points to the center of the earth, and the gravitational force generated by the objects that are not at the poles of the earth due to the action of gravitation (gravity is a component of gravitational force, and gravity is generated because of the presence of gravitational force) does not point to the center of the earth, only the gravitational force on the objects on the poles points to the center of the earth, and we also think that the earth is round.

It is detected by the instrument, when the earth is rotating, the centrifugal force at the equator is relatively large, and it will protrude a little.

You discussed gravity and support together, the gravitational force of an object is broken down into gravity and the centripetal force required to rotate with the earth. So it does not point to the center of the earth, only at the poles and the equator. And the great inverses of the support force and gravity you said are only satisfied at the poles and the equator, but we usually do not pay too much attention to these deviations for the sake of easy understanding, just like many physical endings are satisfied under ideal conditions.

Pure hand-fighting, so tired.

According to Newton's first law, force is not what sustains the motion of an object, so the magnitude of the force on both sides does not reflect the velocity for a motion with a uniform linear motion, where the combined external force is equal to 0. The reason why there is no answer is because the friction force is 1n (strictly speaking), and the friction force is related to the direction of movement, in fact, it is changed to 3m s, and it has no effect.

Acceleration and deceleration are determined by force, so only a short time for the big hand to push the block is accelerated, and after losing thrust, it will continue to slow down until it reaches 0 (without a magic wipe, it will always move at the speed after letting go).

, a2.Quality, initial temperature.

3.Kerosene sheds are built.

4.Unreliable, because the first and bend heat released by combustion cannot be fully absorbed by the water.

Physics says: Unreasonable.

For example: 1. Uniform motion: not at all.

2. Voltage 220V: all approximate values.

3. The force and the reaction force are equal in magnitude and opposite in the opposite direction: the police slap you, do you feel equal? You slapped the police in the face, do you dare to say that it was the other way around?

4. The unit of force is Newton: when the police arrest you, you dare to say: you really can, the police, you have 1,000 Newtons.

Have you ever wondered what it feels like to be physical?