One junior high school physics question, one junior high school physics question.

The quality remains the same. There will be a gap between the bones of the human body, under the action of gravity, the gap will be reduced, in the case of weightlessness in space, the gap will become a little larger, and under the appearance display, the human body will become taller.

After returning to Earth, the gap will gradually return to the state before entering space, after all, the human body is a complex organism, and it is impossible to change too quickly.

The quality never changes. Because when people buy groceries, they buy quality, not weight.

Think for yourself what this means.

The mass is constant, whereas gravity changes.

Mass refers to the amount of matter that makes up an object, it has nothing to do with gravity, although space has no gravity and feels light, but the substance of the object does not change, so the mass is constant.

The gravitational pull decreases, which makes the human skeleton system larger. The gravity decreases, and the mass does not change.

His mass doesn't change He goes into space, because there is no gravity, no pressure, his own cells expand, causing his body to become larger (taller) and his density to become less

No, for example, if you weigh with a balance, the gravity of the left disc is smaller, and the right disc will be smaller, so the weighing result will not change.

It shouldn't change.

This question should not be given to the nature of mass in the case of living things: the mass of an object does not change with changes in temperature, environment, shape, state, position. Because changes in height and mass are important characteristics of the growth and change of organisms, astronauts have undergone many changes in the organism when they enter space or return to Earth, including mass, so his mass has changed.

Well, it sounds like the mass doesn't change with those, no matter in **, unless it's cut off in a piece (meaning it's less), then his mass will change. Otherwise, it won't change.

The mass does not change, the gravity changes, it is almost 0. Because G has changed.

After returning to Earth, the mass is still so much, and the gravity is the same as before.

The mass does not change, and gravity becomes one-sixth; After returning to Earth, the mass remains the same.

g total = f pressure + f pull = 1800n m = 1800n = g g g = 180kg so the density is 180kg 410-2 m3 = 4500kg m3

Because the pulling force is 800 N and the pressure is 1000 Nm, the gravity of the cement slab is 1800 Nm. The mass is 180kg

Because g = PVG, the density = 180kg (4 10-2m3 10n m3) = 4500kg m3

The 3 resistors are in parallel, A2 is the current of R3, A1 is the sum of R1R2 currents, and because the resistance of R2R3 is the same, the current is the same in parallel, so the ratio of R1R2R3 current is 1:2:2, so the resistance ratio is 2:

1:1, after replacing the voltmeter with a series circuit, U1 is the sum of R2R3 voltages, U2 is the sum of R1R2, the series voltage and resistance are proportional, so the voltage ratio is 2:1:

The ratio of 1 to u1u2 is 3:2

If you don't mention it, don't care about the force n pressure = g = 1000 m = g g g = 100 and then use the density formula.

The work done by Xiao Ming has two effects, one is to lift the weight, which is useful work, and the other is to improve the lever, which is.

Useless work. Work on heavy objects.

w1=g1h=15*

The useful work that Xiao Ming does with the lever is w1=

Work on the lever (find the center of mass of the lever, since the lever is homogeneous, the center of mass is at the geometric center, i.e. at the center point of the lever).

w2=g2h=5*

The efficiency is =w1 (w1+w2)= *100%=75%.

From the meaning of the title: the power arm is twice that of the resistance arm, the resistance is 15N+5N=20N, the power * power arm = resistance * resistance arm So F*2=20N*1 F=10N W Total = Fs=F2H=10N*

w useful = gh = 15n * so mechanical efficiency = w useful w total =

Solution: Because w amount = 5*

So w total = w has + w amount =

Then mechanical efficiency = w useful w total =

Considering a,b as a whole, it moves in a straight line at a uniform velocity, so the horizontal direction is subjected to a pair of equilibrium forces, so the friction force between a and the ground is 100n, and the answer a is yes.

There is no friction between b and a, so c is right.

Hence the answers a, c

A, you can look at AB as a whole, then only F and friction, so choose A

If you don't understand yet, you can ask me.

This problem is easy to solve.

It should be gh+g s

Well, it's hard to understand that method, so I'll tell you another method, create your own!

First of all, separate the water from the piston, first calculate the pressure of the water on the bottom of the container, which is PGH, and then, you think, how does the piston float? It is the upward buoyancy of the water to the bottom of the piston, this buoyancy is equal to the gravitational force (the piston weight is not counted), lz should know that the action of the force is mutual, so the piston also gives the water a downward reaction force, where does this force go? It becomes the water to the bottom of the container, which is GS

So, the force at the bottom of the container is the addition of the two forces, which is gh+g s, understand?

If you don't understand me, I'll give you an answer.

Completely hand-to-hand .........

This is characteristic of liquid pressure and is only associated with high and liquid density.

So it should be PGH

The mass is 540g, aluminum=

So the lead ball removes the volume of the body of the hollow part:

v = i.e. 200cm).

Therefore, the hollow volume is 360-200 = 160 cm 160 cm water weight m =

That is, 160g, so the total mass after filling with water is 540 + 160 = 700g

The mass is 540g, aluminum = so the volume should be 200cm, and the hollow volume is 360-200 = 160The weight of 160cm water is 160g, and the total mass is 700g

So the hollow part of 160 makes the density of the water outside it 1, you can do the math yourself.

Is it a shot put? So why tell the density of aluminum???