High School Physics! It s hard!! Sophomore physics questions are very, very difficult!!

Since the particle moves in a circular motion, the centripetal force is equal to the centrifugal force. The magnitude of the tangential acceleration is a1 and a2, respectively.

v^2/r=a1 v=v0+a2t

v-v0)/t=a2

Because a1=a2

v-v0)/t=v^2/r

Simplify. v-v0)r=v^2t

vr-v0r=v^2t

Just solve the quadratic equation.

Normal acceleration is centripetal acceleration = v method.

Tangential acceleration and particle velocity = v = v0 + at

v method = v square radius.

Centripetal acceleration points to the center of the circle, if understood in a narrow sense, it means that when the object is moving in a circle, the centripetal acceleration points to the center of the trajectory circle.

However, circular motion is still a type of generalized curvilinear motion, and for curvilinear motion, acceleration is divided into tangential acceleration and normal acceleration.

The tangential acceleration is in the same direction as the velocity of the point, and the normal acceleration is perpendicular to the velocity direction of the point.

For general curves, the normal acceleration actually points to a point, which is called the center of the curvature circle of the curve at that point, so the centripetal acceleration is also centripetal acceleration for the center of the curvature circle.

After the ordinary curvilinear trajectory is specialized into a circular trajectory, the tangential acceleration is zero, and the normal acceleration becomes what is commonly referred to as centripetal acceleration.

If the velocity is v after time t.

Tangential acceleration = (v-v0) t

Normal acceleration = v*v r

Establish the equation and denote v in t.

The amount of electricity that passes through each section of the circuit (in the conductor and in the solution) per unit time is the same.

In a solution, the amount of charge of the cation flowing through a section during this time is IT 2, and the amount of charge is the section of the section where the anion of IT 2 passes in the opposite direction. The solution is electrically neutral everywhere, so there must be cations with an electric power of it running to the copper plate during this time.

We can take an example, as shown in the figure below, there are two classrooms with two doors C, D, A and B, and there are many male and female students in areas A and B, and the ratio of men and women in both areas A and B is 1:1. In a certain period of time, there are n male students from area B through the section (dotted line) to area A, and at the same time there are n female students from area A through the section (dotted line) to area B, so that the number of male students in zone A is 2n more than the number of female students (if you look closely).

If you want to ensure that the ratio of men to women in Zone A is still 1:1, you have to have 2n male students out of Gate C.

Explanation of BCD: The process of electrolysis converts electrical energy into chemical energy and internal energy. UIT is calculated as the total electrical energy consumed, and UI is calculated as the total power consumed.

i2RT is only the internal energy part of the conversion of electrical energy, and i2R is only converted into power.

aAccording to the definition of current, it can be known that it is right.

C is right. In b, UIT is equal to the heat produced by the electric current and the heat produced by the chemical reaction.

From the fact that D is right, you can know that D is wrong.

I can't eat hot tofu in a hurry, take my time, don't be in a hurry, understand the simplest knowledge points of each section, and then do difficult problems, and don't simply improve your physics scores by doing a lot of problems, this is an unwise choice, your poor grades indicate that the knowledge points are not firmly grasped, and some knowledge may seem to understand or not, so you are not sure when doing the questions, and you are not proficient in the use of formulas. So I suggest you don't do a lot of puzzles, start with the simplest, find confidence, and then work your way up to the top of your physics grades.

b should be uit = joule heat + chemical energy.

d is UI = heating power + converted into chemical energy power.

Remember, the formula for heat is: q=i2rt, only pure resistance, that is, resistance that only heats heat, because only heat, all formulas are equal, in this case, q=i2rt=uit=u2 r (the second and third equal signs are true).

So b is wrong because it is not a pure resistor. It not only generates heat, but also converts it into chemical energy.

The total amount of energy expended is equal to w=IUT which is absolute. Here u is the voltage of the trunk (non-branch). i is the trunk current.

So C right. And the power to convert electrical energy into chemical energy p=ui-i2r is the total power minus the power to generate heat.

What you should keep in mind is that the design to heat, Joule heating, is the total work of i2rt or i2r, is the uit, and the power is ui

Useful work is all total work minus heat, and sometimes it is a little special.

It's hard to be funny, it couldn't be easier.

p=ei: refers to the total power consumed by the power supply in the circuit. It is the power of the electrostatic force to do the work in the circuit.

e=w q: refers to the work done by the power supply electromotive force equal to the internal non-electrostatic force of the power supply to move the unit positive charge from the negative pole of the power supply to the positive pole. Note:

w is the work done by the non-electrostatic force inside the power supply, which are different. p = w t in w is the work done by the electrostatic force e, u is different.

e is the magnitude of the work done by the non-electrostatic force inside the power supply, and the magnitude of the energy that other forms can be converted into electrical energy.

u is the magnitude of the work done by the electrostatic force in the circuit, and the magnitude of the energy that is converted into other forms of electrical energy.

Let the bottom of the slope be the O point. then OA=5cm, OB=12cm, OM=10cm

Because the origin of the coordinates is set as m, Lachan needs to know the length of AM and BM in order to obtain the bridge mark of the sitting section of A and B.

am=om-oa=5cm

bm=ob-om=2cm

And because the downward slope is in the positive direction, the coordinates of A are 5, and the coordinates of Wheel Burning Dust B are -2

The two ropes are symmetrical and have the same pulling force, both of which are g

When the two ropes are close together, the elongation remains the same, the tensile force remains the same, and the total tensile force is 2g

It can be obtained from the interaction force, g = 2g

Answer: 2g

Idea: In both cases, the elongation of the rope is the same, and the elastic coefficient is also the same, so the force is also the same. In the first case, the size is g, so the second is also g, so an object 2g in size should be hung.

At this time, it should be 2g specific force analysis. When one hundred and twenty degrees are known, the force of each rubber is one g, then when the force of each rope is also one g, the rope can be elongated to 1, then the net force is two g, then the weight is two gFinished, trouble points are given.

From s=(at 2) 2 we get 125=a*10 2 2=50a, so a=

Force analysis mgsin -f=ma and know sin = from the geometric relationship

g takes 10 then there is 5m-f=so f= g=mg

1 2 * at square = s

a = the force of gravity along the inclined plane f = mgsin (is the inclination angle of the inclined plane) f = mg*

The resultant force along the inclined plane = f-f = ma

f=f-ma= s/s2

f/g=

(mg + fsin37°) = fcos37° to substitute the data, find = 4 23

a = 1/m ( fcos37° -mg - fsin37°)

Substituting the data, find a = 23 12 m s 2