Xiao Li borrowed a copy of space exploration from the library, with a total of 132 pages. After 356 days, there were 72 pages left. How many pages did she read every day? How many days did she read every day?

132-72 is 60 pages

Xiao Ming and Xiao Li start from village a to village B at the same time. Xiao Li's speed is 4 kilometers per hour, Xiao Ming's speed is 5 kilometers per hour, and Xiao Li arrives 15 minutes later than Xiao Ming
Xiao Ming and Xiao Li set out from village a to village B at the same time. Xiao Li's speed is 4 kilometers per hour, and Xiao Ming's speed is 5 kilometers per hour. Xiao Li arrives 15 minutes later than Xiao Ming to find the distance between village a and village B. if they set out at the same time, how far away from village a will they meet

The distance between villages a and B is x km
X/4-X/5=15/60
X/20=1/4
X=5
The distance between village a and village B is 5 km
Encounter time = 5 ÷ (4 + 5) = 5 / 9 hours

Two ways to solve mathematical problems
① If X & sup2; + 1 / x = 5, find the value of x ^ 4 + X & sup2; + 1 / x ^ 4-x & sup2; + 1
② Donghai forest farm has a number of afforestation tasks, which were originally planned to be completed by 35 people within a certain period of time. In actual afforestation, the tools were changed, which doubled the labor efficiency of each person. Now only 20 people are sent to work. As a result, the task is still completed two days ahead of schedule. How many days are the original plans to complete the task?

1. There may be problems with the title
2. Set the original plan to complete the task in X days, and the efficiency of each person is set to y
35xy=1 （1）
20（x-2）*2y=1 （2）
(2) The formula is divided by (1)
8（x-2）/7x=1
Yide x = 16

How many calories is a kilo of meat equal to

A catty of fat pork contains: heat 1975 kcal; protein 66 g; fat 185 g; carbohydrate 12 G
A catty of lean pork contains 615 kcal of calories, 106.5g of protein, 31G of fat and 7.5G of carbohydrate

If X & # 178; - 13X + 1 = 0, find the number of the book represented by the fourth power of X + the negative fourth power of X

X = 0 is not the solution of x ^ 2-13x + 1 = 0,
Deformation x + 1 / x = 13
x^4+1/x^4
=(x^2+1/x^2)^2-2
=[(x+1/x)^2-2]^2-2
=27787
One digit 7

The 220 V 100 W bulb is connected in series with a certain value resistor. In the 220 V circuit, the resistance of the lamp plate is reduced to 64% of the original value

The title must be wrong. It should be "the power of the light bulb is reduced to 64%"
First calculate the resistance of the lamp: R1 = u ^ 2 / P = (220 V) ^ 2 / 100 W = 484 Ω
Then calculate the current in the circuit after series resistance: I = under root sign (P / R) = under root sign (64W / 484 Ω) = (4 / 11) a
Re note the voltage at both ends of the bulb: U1 = IR1 = (4 / 11) a * 484 Ω = 176v
Then calculate the voltage at both ends of resistance R2: U2 = u-u1 = 220v-176v = 44V
Resistance R2: R2 = U2 / I = 44V / (4 / 11) a = 16 Ω
Finally, calculate the power of the resistor: P2 = u2i = 44V * (4 / 11) a = 16W
Note: in the middle process of physics calculation, the calculated number must keep the open fraction, so that there will be no error in the calculation of the final result. Otherwise, the final result will be much worse than the correct result

When an object moves in a straight line with uniform acceleration, the displacement in the first second is 3.6 m, and the velocity at the end of the second is 6 m / s

The displacement of the 1s is 3.6m. If s = v0t + (1 / 2) at ^ 2, V0 + A / 2 = 3.6 (1)
The velocity at the end of the second second second is 6 m / s. substituting v = V0 + at has V0 + 2A = 6 (2)
(1) (2) a = 1.6 m / S ^ 2 V0 = 2.8 m / S
Displacement in 7S
△s=s7-s6=v0(7-6)+(1/2)a(7^2-6^2)=2.8*1+(1/2)1.6*(49-36)=13.2m

The meaning of all symbols in junior high school physics

5: Speed
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 = F1-F2 direction is opposite, F1 > F2
Buoyancy: F floating (n) f floating = g object - G view (g view: gravity of object in liquid)
Buoyancy: F floating (n) f floating = g object (this formula only applies to floating or suspending objects)
Buoyancy: F floating (n) f floating = g row = m row, g = ρ liquid GV row (g row: the gravity of the discharged liquid; m row: the mass of the discharged liquid; ρ liquid: the density of the liquid; V row: the volume of the discharged liquid (i.e. the volume immersed in the liquid))
Balance condition of lever: f1l1 = f2l2 (F1: power; L1: power arm; F2: resistance; L2: resistance arm)
Fixed pulley: F = g object, s = H (F: the tension on the free end of the rope; G object: the gravity of the object; s: the distance that the free end of the rope moves; H: the distance that the object rises)
Moving pulley: F = (g object + G wheel) / 2 s = 2 h (g object: gravity of object; G wheel: gravity of moving pulley)
Pulley block: F = (g object + G wheel) s = n h (n: number of segments of rope passing through movable pulley)
Mechanical work: w (J) w = fs (F: force; s: distance moved in the direction of force)
Active work: wyou = g object H
Total work: wtotal wtotal = FS when the pulley block is placed vertically
Mechanical efficiency: η = Wye / wtotal × 100%
Power: P (W) P = w / T (W: work; t: time)
Pressure P (PA) P = f / S (F: pressure; s: stressed area)
Liquid pressure: P (PA) P = ρ GH (ρ: density of liquid; H: depth [vertical distance from liquid surface to desired point])
Heat: Q (J) q = cm △ t (C: specific heat capacity of material; m: mass; △ T: temperature change value)
Heat released by fuel combustion: Q (J) q = MQ (M: mass; Q: calorific value)
Current I (a)
Voltage U (V)
Resistance R (Ω)
Q: Charge quantity (Coulomb)
Electric work: w (J) w = uit = Pt (U: voltage; I: current; t: time; P: electric power)
Electric power: P = UI = I2R = U2 / R (U: voltage; I: current; R: resistance)
The relationship between electromagnetic wave velocity and wavelength, frequency: C = λ ν (C: wave velocity (the wave velocity of electromagnetic wave is constant, equal to 3 × 108m / s); λ: wavelength; ν: frequency

As shown in the figure, there is a smooth hole o on the smooth horizontal table. A light rope goes through the hole. One end is connected with a small ball a with mass m = 1.0kg, and the other end is connected with a heavy object B with mass m = 4.0KG
(1) When ball a moves in a circle with radius r = 0.1M at a uniform speed and is equal to 10rad / s, what is the pressure of ball B on the ground?
(2) When the angular velocity of ball a is large, object B will start to leave the ground? (G is taken as 10m / S2)

In the application of the law of conservation of momentum, there are many topics about the deformation and comprehensive application of the "bullet hitting wood block" model, We can grasp the physical essence of the problem and solve it quickly
I. The first case is that the bullet hits the block but does not penetrate it
Model 1 is shown in Figure 1. The wood block with mass m is placed on a smooth horizontal plane, and the bullet with mass m shoots horizontally at the velocity V0 (assuming that the bullet is subject to constant resistance in the wood block), but it does not shoot through the wood block?
(1) How long does it take for the object to leave the car?
(2) during the sliding process of object M2 on the vehicle, what are the positive work done by M2 on the friction of the vehicle and the negative work done by M2 on the friction of M1? (g = 10m / s)
(1) after the object M2 slides onto the trolley, it begins to decelerate uniformly to the right under the action of the sliding friction of the trolley to the left. At the same time, the trolley begins to accelerate uniformly to the right with zero initial velocity under the action of the sliding friction of the object to the right. When the object leaves the trolley, that is, the position difference between the two is equal to the length of the trolley L, According to Newton's second law
a1＝（μm2g）／m1＝μg＝0.5m／s,
a2＝－（μm2g）／m2＝－μg＝－0.5m／s．
If the object leaves the car after time t, then
L＝s2－s1＝（v0t－（1／2）a2t2）－（1／2）a1t2,
By substituting A1, A2, l and V0 into the above formula, we can get the following results
T1 = 1s, T2 = 4S (rounding off)
(2) from T1 = 1s, we know that the displacement of the object is
s2＝v0t－（1／2）a2t2＝2．25m．
The position of the trolley is S1 = (a1t2 / 2) = 0.25m
W1 = μ mgs1 = 0.125j,
W2＝－μmgs2＝－1．125J．
It can also be found from the kinetic energy theorem that when the object is separated from the trolley, the velocity of the object is
v2＝v0－a2t＝2m／s,
The speed of the trolley is V1 = a1t = 0.5m/s,
For the kinetic energy theorem of the car, W1 = (1 / 2) m1v12 = 0.125j
If we use the kinetic energy theorem for an object, we get
W2＝（1／2）m2v22－（1／2）m2v02＝－1．125J．
The essence of the "bullet hitting wood block" model is to realize the change of momentum, kinetic energy and energy of the object in the system under the impulse of a pair of force and reaction (internal force of the system), Therefore, the total momentum of the system remains unchanged. Therefore, the scientific thinking method of "model" can be used to broaden the scope of "bullet hitting wood block", so as to quickly and accurately solve difficult problems, train students to solve more than one problem and solve more than one problem, so as to achieve the effect of cultivating students' innovation ability

The more the current of a certain lightning is 2 times 10 to the fourth power a, and the voltage is about 1 times 10 to the eighth power V, the longer the discharge time is 0.001 S. the electric power of this lightning is 0.001 s

Xiao Li borrowed a copy of space exploration from the library, with a total of 132 pages. After 356 days, there were 72 pages left. How many pages did she read every day? How many days did she read every day?