Solve a few physics problems, solve a physics problem

All submerged in the liquid to be tested touching the bottom and walls of the container.

Wait a little for stability.

Continue to remain in the liquid being measured to be level with the upper surface of the liquid column in the thermometer.

How to use the thermometer.

Estimation: Estimate the temperature of the liquid to be measured before measuring;

Select: Select a thermometer with the appropriate range according to the estimated temperature.

No: The glass bubble of the thermometer should be fully submerged in the liquid to be measured, but do not touch the bottom and walls of the container.

Wait: Wait a while for the glass bubble to be fully submerged in the liquid to be measured.

Steady: Wait for its indication to stabilize before reading.

Stay: The glass bubble should remain in the liquid being measured during the reading.

Flat: The line of sight should be level with the upper surface of the liquid column in the thermometer.

Note: Correct recording of measurement results.

1. Completely immersed in the liquid to be measured, in contact with the bottom of the container and the wall of the container.

2. Keep the indication stable for a period of time.

3. Continue to stay in the liquid to be measured perpendicular to the thermometer.

Sufficient contact with the liquid to be tested Contact the wall or bottom of the container.

After a while, it is stable.

Full contact with the liquid to be measured is level with the upper surface of the liquid injection.

1) The glass bubble of the thermometer should be immersed in the liquid to be measured; Do not touch the bottom of the container or the walls of the container; (2) After the thermometer glass bubble is immersed in the measured liquid, wait for a while, and then read it after the thermometer is stable; (3) The glass bubble should continue to remain in the measured liquid during reading, and the line of sight should be level with the upper surface of the liquid column in the thermometer.

The answer is definitely a. The energized coil is equivalent to a small magnetic needle, then the N pole of the small magnetic needle is outward, and the S pole is inward. Defined by the direction of the magnetic field, the small magnetic needle should point in the tangential direction of the magnetic inductance line at the location.

Therefore, the coil must rotate, and after rotation, the S pole of the small magnetic needle will be opposite to the N pole of the magnet, so it will be attracted by the magnet and move closer to the magnet.

The fork in the diagram is the direction of the magnetic field lines of the magnet.

D should be chosen

1.The hook is squeezed into a smooth wall to zero the air in the trays, and the suction cups can be sucked on the wall by atmospheric pressure. The amount of suction power depends on the size of the area.

2.The force of each suction cup f = atmospheric pressure * area = p * s = 100,000 * atmospheric pressure is approximately equal to 100,000 pa).

Since there are 4 suction cups, multiply by 4

It is known that the statue weighs 1,617 tons.

Seeking: The gravitational force on which the statue is subjected.

Solution: According to g=mg=16170000N

Known: the total gravity of the statue f=g=16170000n Find: the pressure of the statue on the horizontal plane.

Solution: According to the principle of mutual equality of forces, the pressure of the statue on the horizontal plane is equal to its own gravity = 16,170,000n

Seeking: The support surface is pressured by the statue.

It is known that the pressure of the statue on the horizontal plane is 16170000N, and the contact surface between the statue and the horizontal plane is 400

Solution: According to the formula p=f s

p=16170000n 400=40425pa Known: Xiao Li's mass is 50

Seeking: Xiao Li's gravity.

Solution: According to g=mg

The gravity of Xiao Li is g=500n

It is known that the gravitational force of Xiao Li Tong = the pressure he gives to the ground f = 500N, and the contact area between him and the ground is.

Seeking: Xiao Li's pressure on the ground.

Solution: According to p=fs

p=12500pa

Note: where g is a constant, which can be equal to or 10

Gravity: g=mg=1617*1000* Note: First, the ton is converted into kilograms, so multiply by 1000, and then multiply by the formula by the gravitational acceleration g, whether it is multiplied by 10 or according to your course.

Support Force: The support force is equal to the gravitational force due to the balance of forces.

Pressure: p=f s=g (40*10), description: 40*10 is the contact area.

Known: mass m = 50kg, acceleration due to gravity g =

Find: gravity g solution: according to: g=mg=50*

Known: The support force is equal to the gravitational force, i.e. n=g=......, contact area s = find the pressure p

Solution: According to: p=f s=g s=......

Description: All the gs are taken as 10 according to your needs or, the places that need to be calculated are too lazy to count, you can calculate them yourself.

1.Known: m = 1617 tons = 1617000kg s = 40m * 10m = 400m2 g = 10n kg

Find: gravity g pressure f pressure pressure p

Solution: (1) g = mg = 1617000kg * 10n kg = 16170000n

2) F pressure = g = 16170000N

3) P=F pressure s=16170000N 400m2=40425pa2Known: m = 50 kg, g = 10 n kg, s = find: gravity g pressure p

Solution: (1) g=mg=50kg*10n kg=500nf f=g=500n

2）p=f/s=500n/

The total gravity of the statue is =1617 tons g=

First, gravity g=m*g=1617*1000*10 pressure is equal to gravity.

The pressure is equal to the pressure divided by the area.

The second question, gravity = m*g = 50*10

Pressure divides the area by pressure, that is, gravity divides the area.

Do the math yourself.

1.(1)g=mg=1617*10^3kg*10n/kg=(2)n=g==

3）p=g/s=

2(1)g=mg=50kg*10n/kg=500n(2)p=g/s=500n/

As for the known conditions, it is okay to write what you see in the title, this is not important).

Design a timber of uniform thickness, indicating that the center of gravity is in the center of the timber, place the timber on the log, the person stands at one end of the timber, and move the contact point between the timber and the log until the person stands on the timber and reaches the balance (similar to a seesaw) The lumberjack stands on one end of the timber so that the timber is just lifted (that is, the human body and the timber are in balance), then the measurement.

The distance from the human body to the support point x

and the distance y from the support point to the center of the timber, which is the weight of the timber divided by y by x*the weight of the lumberjack.

Measurement: The lumberjack's weight must be known for his or her height and can be used for his or her arm span (generally arm span height).

Foot plate length The length of the forearm).

Similarly, you can use shoe size to measure size 42 shoes, which are generally 26 cm long, size 41 shoes seem to be size 40, and size 40 shoes look like 25 cm

Place the timber on a raised mound with the whole lump suspended except for the fulcrum, and the person stands on the edge of the shorter end and moves the timber to keep the balance until the equilibrium is reached. Record the ratio of the length of the timbers on both sides of the fulcrum: if the distance from the position of the person standing to the fulcrum is 1 n of the whole timber, the moment balance can be calculated.

Let the mass of the person be m and the mass of the wood be m, then: f person l person + f short wood l short wood.

F long wood l long wood.

m*(1 n)+(1 n)m*(1 2n)=m*This can be calculated: m=*m

Therefore, you only need to know the proportion of wood at both ends when maintaining balance to know the quality, and this length ratio should be easy to compare.

Then cut down the next long log, make an equal arm lever, and put the man and the long wood aside, to see if it is balanced, if not, the wood can be divided into equal parts, and marked, marked to a grid. Finally, choose the middle as the fulcrum. And then anything equal to the weight is good, recorded well.

Then you can know how much each slot occupies. Finally, you can "compare" your weight with the wood on the lever. In this way, you can see how much heavier or lighter the wood is heavier than yours!!

Pure hand-played. If the landlord can understand, he may wish to adopt it! Maybe the idea is not well expressed, please read it a few more times.

The answer is d.

Solution: Let the tension of the small rope be f, oo = h

For the analysis of the force of the ball, the resultant triangle is made, and the two triangles are similar, so :

f l1 = m1*g h (proportional to the corresponding edges), the same goes for

f/l2=m2*g/h

Therefore: m1=f*h (l1*g) The same goes for :

m2=f*h (l2*g) so: m1 m2=l2 l1=:24

Let's choose C.

Let the distance from the pulley to the center of the hemisphere be l0; The force on the rope is FL0 L1=M1G F;

l0/l2=m2g/f;

Compare the above 2 formulas.

p = density multiplied by g multiplied by h

The cubic of the first question is multiplied by 10 times 4. Unit Pascal.

The end result was 32,000 Pa.

The third power of the second question is multiplied by 10 times (. The unit is Pascal.

The final result was 28,000 Pa.

The third question uses f=ps, and the pressure of the second slow section is multiplied by the area, and the area is used by the area formula of the garden, and the unit conversion is noted.

In the end, the answer is pretending to grind.

The circumference rate of the circle disturbs the reputation.

1. The right focus of the left convex lens coincides with the left focus of the right convex lens; The main optical axis also coincides.

2. Place the convex and concave lenses side by side, the main optical axis coincides, and the right focus of the convex lens coincides with the right imaginary focus of the concave lens, and the parallel light is emitted to the convex lens from the left side.

B should be chosen

The reason is that when the two rings are stable (i.e., in static equilibrium), we analyze the forces on the ring q in three (ignoring the static friction force) - the force f along the ob, the tension p of the rope acting on the ring q, and the reaction force n of the pole ob on the ring q (which should be perpendicular to the pole ob to the rope - outward). If the force p is decomposed into two components, p1 and p2, respectively, in the horizontal and vertical directions, where p2 and n are in equilibrium (equal in magnitude and opposite in direction), and p1 and f are in equilibrium (equal in magnitude and opposite in direction, f=-p1), p=p1 sina can be obtained by solving the triangle, that is, p=-f sina ignores the direction and only considers the absolute value is p=f sina

The graphics can be drawn according to my description, you can draw them yourself.

Because the light loop P is only subjected to the tension of the string and the pressure of the OA rod on him, in order to balance, the two forces must be equal in magnitude and in opposite directions. In what direction is the pressure of the OA rod to P, we know that the pressure is always perpendicular to the OA rod, so the string is also perpendicular to the OA rod.

Now for the analysis of the force on Q, Q is acted on by three forces, one is the constant force F, the tensile force of a thin rope, the size is not known, the direction is perpendicular to OA, that is, the angle with OB is 90°+A, and the third force is the pressure of OB to Q, and the direction is perpendicular to OB. According to the equilibrium conditions, we know that the component of the string in the ob direction must be equal to the magnitude of f and in the opposite direction.

So what is the component of the string in the ob direction? We already know that the angle is 90+A, then the component force is ICOS (90°+A), and I is the tensile force of the string. ICOS(90°+A)=-F=-Isina gives F=Isina and gives i=F Sina

b right. When stable, the elastic force of the OA bar to the P-ring is a vertical OA bar (otherwise it will move); For the Q ring, it is subjected to three forces: the string tension t, the tension f along the ob rod, and the elastic force n of the ob rod, and the net force is 0.

The resultant force of the three forces of the q ring is 0, and combined with the knowledge of triangles, f t sina is obtained

The size of the string tension is t f sin