Finding the formula of physics in the second grade of junior high school (PEP)

Density definition formula ρ = m / V
Buoyancy formula F = ρ liquid GV discharge
Weighing method f floating = G-F '
Floating and floating f-floating = g
Archimedes principle f = g row
Cause f floating = f up - f down
F floating at bottom = G-N
Power (Mechanical) definition P = w / T vehicle power P = FV
Work (Mechanical) definition formula w = FS total work w total = w useful + W amount
Lever balance condition f1l1 = f2l2
Definition formula of mechanical efficiency: η = w useful / W total lifting weight: η = GH / Fs horizontal moving weight: η = FS / Fs
Wtotal = FS w useful = GH
Mass m kg m = PV
Temperature T ° C ° C
Velocity v m / S M / S v = s / T
Density p kg / M & sup3; kg / M & sup3; P = m / V
Force (gravity) f Newton (cow) n g = mg
Pressure P Pascal PA P = f / S
Work w Joule (joule) J W = FS
Power P watt W P = w / T
Current I a (a) a i = u / R
Voltage U V U = IR
Resistance R ohm (Ω) r = u / I
Electric work w Joule (joule) J W = uit
Electric power P watt (watt) W P = w / T = UI
G 9.8 N / kg

Summary of all the formulas of physics in the second grade of junior high school

Physical quantity (unit) formula remarks the deformation velocity V (M / s) v = s: distance / T: time gravity g (n) g = mg m: mass G: 9.8n/kg or 10N / kg density ρ (kg / m3) ρ = m / V M: mass V: Volume resultant force F (n) direction is the same: F = F1 + F2 direction is opposite: F combined

People's education press second year Physics Volume 1 Chapter 1 Lesson 1 exercises

1. Prove that the table is vibrating: put a glass of water on the table, sprinkle some sand, etc
2. Time = distance / speed attention unit
1000km=1000000m
1000000 / 340 = 2941 seconds
3. If the pipe is long enough, two sounds can be heard: one from the solid, the other from the air
If the tube is not long enough, the interval between the two sounds is too short for the human ear to distinguish
4. Echo ranging 340 * 1.5/2 = 255 M
5. Small and large temperature

How much is a piece of cloth

One horse is four feet, one foot is ten feet, one meter is three feet,

A cuboid wood is 4 meters long. After it is cut into two sections, the surface area increases by 400 square centimeters. How many cubic meters is the volume of this wood?
Find the formula, process, method!

400 divided by 2 = 200 square centimeter = 0.02 square meter
0.02x4 = 0.08m3

How to draw an axisymmetric figure with x = - 1

If x axis is symmetric, then y in the original function is replaced by - Y
For your question, since there is no y in the function, the axisymmetric figure is itself, that is, x = - 1
If the Y axis is symmetric, then x in the original function is replaced by - X
That is: - x = - 1
It is reduced to: x = 1

A square wooden box, measured from the outside, is 42 cm long and 2 cm thick. How many cubic decimeters is the volume of this wooden box?

(42-4) ^ 3 = 54872 square centimeter = 54.872 square decimeter

How to find the Fermat point of triangle

In a triangle, the point with the smallest distance to the sum of three vertices is called the Fermat point of the triangle
(1) If the three internal angles of the triangle ABC are less than 120 degrees, then the three distance lines exactly bisect the circumference of the Fermat point. Therefore, the Fermat point of the triangle is also called the equiangular center of the triangle
(2) If a triangle has an internal angle not less than 120 degrees, then the vertex of the obtuse angle is the point with the smallest sum of distances

As shown in the figure, de ‖ BC, and DB = AE, if AB = 5, AC = 10, then the length of AE is___ ．

Let DB = AE = x, ∵ AB = 5, AC = 10, ∵ (5-x): 5 = x: 10, then x = 103, that is, the length of AE is 103

F (x) = 1 / x-3, the increase and decrease interval of this function can be obtained according to the derivative

x> When f '(x) = - 1 / (x-3) ^ 23, it is minus
x

Finding the formula of physics in the second grade of junior high school (PEP)