Trouble to explain in detail, physics problems, trouble everyone to solve physics problems

1. From the accuracy of the microscope to 10-2mm, the index value of the microscope is known, and the reading is, indicating the accurate value and the estimated reading value contained in the reading. According to the reading method of "when reading, the next digit of the graduation value should be estimated", it can be seen that the reading number is correct.

2. The magnification of the microscope is 50, although the measured object and the ruler are magnified by 50 times, but the magnification value of the ruler and the size of the marked data will not change after magnification, so the reading is the actual data to be measured. Therefore, the measurement data should ultimately be recorded as:

Conclusion: Pick B

Answer: C Analysis: The reading microscope is a kind of reading device in optical and precision mechanical instruments, which is suitable for the alignment inspection and measurement of the scribe or dial of the scribe or dial in the measurement room or precision scale workshop of the relevant measurement unit.

The measurement data should ultimately be noted as, option c is correct.

It doesn't matter how much magnification is, since it's a reading, then the reading should be accurate, if you have to multiply it by 50 Shenma, it's too complicated, then there is no need to make this kind of instrument, magnification is just for the convenience of reading. Since it is the micrometer principle, it should be the estimation of the sum, so B should be chosen

I think it should be d Since it is enlarged, it must be getting smaller and smaller.

It is obtained from the envy of the closed e nδ calendar pai chang δt limb lδi δt.

400=l2/

The solution is l=400000h

The self-inductance coefficient is l

Analyze the parabola first, and we can know that the movement time of this particle is t=s v, so the vertical displacement of this particle is h=1 2gt squared.

The rings are then analyzed. From the perspective of conservation of energy, the kinetic energy of the small ring is 0 at the beginning, and then the gravitational potential energy is converted into kinetic energy, so, 1 2mv ring square = mgh where the v ring is the final rate of the small ring.

Since the trajectory of the small ring strictly follows the orbit, the final velocity of the small ring is the same as the final velocity of the particle motion. So you also need to know the tangent of the last point of the track and the angle between the ground!! It can be known that the horizontal velocity of the mass is still v, and the vertical velocity is u=gt=g*s v

So their combined velocity v sum is v squared plus u squared under the root number (because the horizontal and vertical angles are right angles, the Pythagorean theorem).

Then analyze the small ring, its velocity at this time is the same as the velocity direction of the particle, so the velocity of the small ring can be decomposed into horizontal and vertical directions, and the proportional relationship can be obtained.

v level v ring = v v combination to find v level.

Feel free to ask.

The total length is 18m, then the horizontal displacement is 9m (because it is close to the net and falls on the bottom line), and the vertical displacement is .

Let the time be t,;

t=;v=9m/;

Known: The mass of 30ml of oil is.

Find: 30m of the quality of oil.

Solution: Method 1: =m1 v1=

m= v= method two: same according to density.

m/v=m1/v1

m=m1v/v1=

Answer:..

Known: p1=p2, m1= v1=30ml v2=30m Find: m2

where the subscript 1 represents the oil taken out, and 2 represents all the oil in the car) solution: p1=m1 v1=.

p2=p1=..

p2=m2/v2 m2=..

Is the solution in junior high school ......I forgot a little bit.,Do you want to set it up--I'm not going to set it anyway.,Handle the details yourself.。

It's all in the title.

Known: m=,v=30 ml=3*10 (-5) m3,v=30 m3

Solution: =m v= (Do your own calculations, algebra formulas will always be, remember to bring units) m= v= (answer - -

(1) The centripetal force is provided by gravity, there is MV2 r=mg, and v1= gr is obtained

2) The gravitational force provides the centripetal force, and there is g mm r 2 = m (2 t) 2 r.

r=r+h

Find the rated current of the bulb and fiercely: i1=p1 u1=1 3a, i2=p2 u2=1 2a

Therefore, the maximum allowable current of the series connection can be found as the maximum allowable current of 1 3A: R=U and P, R1=27 ohms, R2 24 Ohms.

So the total voltage U i(R1+R2)=17V

p i r, p1 = 3w, p2 = 8 3w