SOS is a master of science, and SOS is a master of physics

Series connection: The circuit elements are connected at one time is called a series circuit, the current path is unique, the switch position is arbitrary, and the addition of bulbs will dim other bulbs.

Parallel circuit: The components are connected in parallel is called a parallel circuit, and the whole circuit forms a broken circuit and disconnects a branch without affecting other branches.

Draw circuit diagram note: must be right angle, the circuit should be drawn with a ruler, draw straight, the circuit original can only be connected up and down or left and right, not in the corner, if there is a parallel connection (the most interesting), according to the "H" type connection, that is, the circuit element (real life) connected to two wires, then the original put "H" in the middle of the horizontal line, do not draw a circuit diagram can not connect a circuit element with a few wires, like up and down left and right wires, even in reality, can not, draw can not, must keep in mind this important practical and easy to forget"H" type circuit. Finally, don't forget how to draw the various originals of the circuit, and draw the standard.

Tandem: i1 = i2 = i3 = ...=in=i total (all parts of the series circuit have equal currents) u1 + u2 + u3 + ....+un=u total (the total voltage of the series circuit is equal to the algebraic sum of the voltages of each part).

r1+r2+r3+…+rn=r total (the total resistance of the series circuit is equal to the algebraic sum of the resistances of the parts).

When the energizing time is the same.

u1 u2=w1 w2=p1 p2=r1 r2 parallel: i1+i2+i3+....+in=i total (the parallel circuit trunk current is equal to the algebraic sum of the currents of each branch).

u1=u2=u3=…=un=uTotal (the total voltage of the parallel circuit is equal to the voltage of each branch) 1 r total = 1 r1+1 r2+1 r3+....+1 rn when the power-on time is the same.

i1/i2=w1/w2=p1/p2=r2/r1

Newton's second law states that the acceleration of an object is proportional to the force exerted, provided that the masses are equal. a=f/m

Object free fall: a=mg m =g

It's not a contradiction at all.

It's not about quality.

It's normal to have to do with quality, that's right.

But gravity is proportional to mass, and in the end mass is reduced to mass, so it doesn't matter.

The premise that has nothing to do with mass is also f=ma, so mg=ma, g=aAnd G is also changing.,Why do I think your question is a bit like a philosophical question?,Don't you want to go to the tip of the horns?。

There is a white solid A, which may contain some of the five substances of K2CO3, BaCl2, Na2SO4, NANO3, and Ba(NO3)2

After adding distilled water and stirring thoroughly, it was filtered, and there was precipitate B and filtrate C

A sufficient amount of dilute nitric acid is added to the precipitate B, and the precipitate is completely dissolved, and a gas that makes the clarified lime water turbid

Silver nitrate solution and dilute nitric acid were added to filtrate C, and no obvious phenomenon occurred According to the above experiments, the following questions were asked:

1) Solid A must contain K2CO3 and BA(NO3)2, there must be no BACl2 and Na2SO4, and there may be nano3, 2) Write the chemical equation that the chemical reaction must have occurred during the above experiment: K2CO3+BA(NO3)2=BAC3 +2KNO3, BAC3+2HNO3=BA(NO3)2+H2O+CO2

— Judgment key——— Spring Sparrow———

Solution: Because of the addition of distilled water and full stirring and filtration, there is a precipitate B, and a sufficient amount of dilute nitric acid is added to the precipitate B, and the precipitate is all dissolved, and a gas that makes the clarified lime water turbid is generated From this, we conclude that the mixture must contain potassium carbonate and a barium salt, and must not contain sodium sulfate

And because silver nitrate solution and dilute nitric acid are added to filtrate C, there is no obvious phenomenon, indicating that filtrate C must not contain chloride ions, so we can be sure that the mixture must not contain barium chloride, and must contain barium nitrate

Therefore, the answer is: 1) K2CO3, Ba(NO3)2; bacl2、na2so4；nano3

2）k2co3+ba（no3）2=baco3↓+2kno3

baco3+2hno3=ba（no3）2+h2o+co2↑

= to the 3rd power kg m v=m = 12kg * to the 3rd power kg m3 = 7200m 30 = 21600m (as for the degree of less aluminum, it depends on what unit it is calculated according to, if it is mass, then you also have to multiply the density of aluminum, if it is volume, it is 21600m) 2f=12n s=100 cubic centimeters = p=f s=12n v= m= v (the density of copper I forgot to flip through the book and there is) 4(1) f pressure = 9n p = 9n (2) f pressure = 9n p = 9n 5

The stress area of walking is one foot Note that the jacket) f=40000pa* g student = 50kg * 10n kg = 500n 500n < 640n he can safely pass through the ice 640n-500n = 140n m object = 140n 10n kg = 14kg Whew! It's finally done, the landlord, study hard, aren't these questions difficult, just think about it.

Trouble, thanks!

1.The ball is subjected to the vertical downward gravity The electric field force in the horizontal direction The tensile force along the direction of the rope contraction The balance of the three forces The rope is broken, that is, there is one less lifting jujube hui tension The ball is affected by the gravity and the electric field force The combined external force is constant, so it accelerates uniformly and moves in a straight line in the opposite direction to the direction of the rope tension

2。Due to the balance of gravity, electric field force, and tensile force. According to the equilibrium quadrilateral rule, the size of f can be calculated, and the value of q can be calculated by f electricity = eq

3.The question asks about the distance to the metal plate, so you only need to calculate the horizontal motion of the ball, the horizontal direction of the ball is only subject to the electric field force, and the distance between the two plates is found by the voltage U, and then the electric field force is found by e and q in the second question, and then the acceleration of the ball in the horizontal direction a can be found according to the distance d acceleration a can be found in time