Ask Physics Questions Ha 75, Ask Physics Questions Ha

The small ball ball is subjected to four forces after starting to move from the A end, the electric field force is QE, gravity mg, pipe wall support force N, friction force F, because the ball is in an unbalanced state at the starting point, it is unbalanced at any position on the inclined tube, and the ball will do reciprocating motion in the " " tube, and finally stop at B. If the whole process of motion is taken as the object of study, the problem will be simplified.

Taking the small ball as the research object, the force is shown in the figure on the right.

As shown, since the work done by electric field force and gravity is independent of the path, and the work done by frictional force is related to the path, let the ball move.

The total distance is s, which is obtained by the kinetic energy theorem:

qelsin — mglsin fs=0 and because f= n

n=(qe－mg)cosθ

Therefore, the total distance of the ball movement can be solved by the above three forms:

s=ltanθ/μ=

At that time, we were dizzy about such unrealistic topics, but when we graduated and came out to work, we realized that all these things were decorations and had no use. Alas, poor student, I really don't know what the education department thinks about making such nerve-wracking topics. Will it increase GDP, increase taxes, or achieve moderate prosperity?

Will the Diaoyu Island problem be solved? Will people's wages go up in this way? Depressed next generation of young people, when will they be able to get out of the dead end of reading dead books?

<> from the diagram above, the answer is A

I am a family member of Ma Junqi, Ma Junqi is a second-degree disability, and he was hospitalized first, and he could have been reimbursed if he didn't get his disability in a hurry

Unreliable. Because the clerk ignored the quality of the hanging plate.

Untie. Set the fulcrum to the length of the hanging plate and the fulcrum to the rod tail length = k

The quality standards are as follows.

Hanging pan か weighing stone mb

The watermelon m is derived from the lever principle, and the system of equations "*" represents the multiplication sign, "means squared (10+mA)k=1*mb [the scale capacity is 10kg, 10 10=1] (m+mA)k= [

m+2*ma)k=[m (20-ma)]*2*mb [according to the above this is m (20-ma)] (there is some abstraction here, please think about it).

The above three equations give the following one-dimensional quadratic equation.

3*m 2-79m-4 3*(m-13) 2+520=0. m=

ma = 2 watermelon weight.

The hanging plate weighs 2kg

Resolve it for a while.

It's finally solved.

This morning I suddenly remembered the crane scales I had seen a few years ago.

The crane scale has a balance point at the other end of the fulcrum when not putting things.

The scale is balanced with the empty hanging plate at this point.

Set the pivot point to the distance: x

Set the distance from the hanging plate to the balance point: y

Set the distance from the equilibrium point to the end of the pole: z

by the principle of leverage.

ma*x=mb*y

10+ma)x=mb(y+z)

m+ma)x=2*mb(y+

From the above three formulas, substitute the known.

m=13+ma

and 10*y=ma*z

3 programs cannot solve 4 unknowns.

If. Use one crane scale to weigh out the hanging plate weight of another crane scale: ma

Substitute m=13+ma to get the solution!

Or use a crane scale to weigh out the actual weight of an object within 10kg: m1 and then read the weight in the double stone scale in the question: m2

Substituting m1 and m2 into the above equation can also be solved!

Please forgive me if there is any inappropriateness in the previous answer!

It should be possible, as long as the scale rod is continuous, the lever grows linearly.

1.It may be that this kind of sound, which is directly heard by people and has spatial distribution characteristics such as azimuth levels, is called the "stereo phenomenon" in nature.

2.Another effect may be that this slight difference in the perception of sound between the two ears is transmitted to the nerves of the brain, allowing us to determine whether the sound is coming from the front right. This is commonly referred to as the "binaural effect".

The watchtower owner is satisfied!

Kicking process: f mg ma, 1050 60*10 60*a, get a when the speed is v a*t when he just leaves the ground, and the maximum height he can rise is v 2 2*g*h

Find, 3 2 2 * 10 * h, so h meters, touch the high score is the distance between the place and the ground that the hand can reach, so.

His grade is m.

Ball C first touches A to take away half of the charge, and ball B contacts first neutralizes and drops half of the charge and then takes away half of the remaining charge, and ball B has twice the charge left. The Coulomb force formula is directly proportional to the product of the electric charge of two point charges, so yes.

Suppose that the original charges are all q, and the polarity is opposite because it is attractable.

The contact between C and A is divided into Q 2

C is in contact with B, first canceling Q 2, and then bisecting, and the result is that B leaves Q 4 force to become F (2*4) = F 8

The amount of change in kinetic energy is equal to the sum of the work done by the forces experienced by the object. The amount of mechanical energy change is equal to the sum of the work done by other forces except gravity and elastic force.

Gravity and tension do positive work, so wf=a, wg=c;

The supporting force of the inclined plane does not do work on the object, and the frictional force does negative work, so w oblique = -b;

Air resistance does negative work, so w gas = -d

Therefore, fill in the first blank [a-b+c-d], and the second blank removes the work done by gravity, and fills in [a-b-d].

Acceleration = f m = 12 (1 + 2 + 3) = 2m SS object 1 is subjected to force f, and the support reaction force n of m2, f-n = m1an=f-ma=12-2*1 = 10n, the force of object 1 to object 2 is 10n, the force on object 1 is 10n, and the force on object 3 is n2, n-n2 = m2a

n2=n-m2a=10-2*2=6n, object 3 is forced by object 2 to be 6n, f=m3a, a=6 3=2).

Therefore, the force of an object with a mass of 2 kg to an object of 3 kg is 6n, and the force of an object of mass 2 to a macro object of mass 1 is 10n

First, find the total acceleration a=2m s

3kg is judged to be f=6n by the lead in the middle of the pie, that is, Huaihe B is given in the same direction as 12N.

A is subjected to a resultant force of 2N, so the force given by B to A is 10N, which is the opposite of 12N.

The three-yard branch a is the same f=ma a=f total rolling finch m total = 12 (1+2+3)=2

f3 = a*m3 = 2 * 3 = 6 2kg to 3kg of retarded min6n

f(1-2)=a*(m2+m3)=2*(2+3)=10n 2kg for 1kg of 10n