Physics means all formulas and letters.

Summary of physics formula in senior one.

First, the motion of the particle (1)- linear motion

1) moving in a straight line at a uniform speed

1. average speed Vping =S/t (definition) 2. Useful inference vt 2-VO 2 = 2as.

3. Intermediate speed vt/2 = Vping =(Vt+Vo)/2 4. Final speed Vt=Vo+at.

5. Intermediate position speed vs/2 = [(VO 2+vt 2)/2] 1/26. Displacement S= V level T = VOT+at 2/2 = vt/2t.

7. Acceleration a=(Vt-Vo)/t With Vo as the positive direction, A and Vo are in the same direction (accelerating) a>0; On the other hand, a < 0

8. It is inferred experimentally that δs = at 2δs is the displacement difference of adjacent consecutive equal time (t).

9. Main physical quantity and unit: initial velocity (Vo):m/s

Acceleration (a): m/s 2 Final speed (Vt): m/s.

Time (t): second (s) Displacement (s): meter (m) Distance: meter speed unit conversion:1m/s = 3.6 km/h.

Note: (1) Average speed is vector. (2) The acceleration is not necessarily high when the speed of the object is high. (3)a=(Vt-Vo)/t is only a measure, not a judgment. (4) Other related contents: particle/displacement and distance /S-T diagram /V-T diagram/velocity and rate/

2) Free fall

1. Initial speed Vo=0

2. Final speed Vt=gt

3. Falling height h = gt 2/2 (calculated downward from Vo position) 4. Inference vt 2 = 2gh.

Note: (1) Free falling body is a uniformly accelerated linear motion with zero initial velocity, which follows the law of uniformly variable linear motion.

(2) A = G = 9.8 m/s 2 ≈ 10 m/s 2。 The acceleration of gravity is smaller near the equator, smaller than the flat in high mountains, and the direction is vertical downward.

3) Throw vertically upwards

1. displacement s = vote-gt 2/22. The final speed Vt= Vo- gt (g=9.8≈ 10m/s2).

3. It is useful to infer that vt 2–VO 2 =-2gs4. Maximum rising height hm = VO 2/2g (from the throwing point).

5. Round trip time t=2Vo/g (time from throwing back to original position)

Note: (1) Full-course treatment: it is linear motion with uniform deceleration, with positive upward direction and negative acceleration. (2) Sectional treatment: the upward movement is uniform deceleration, and the downward movement is free fall, which is symmetrical. (3) The process of ascending and descending is symmetrical, for example, at the same point, the speed is equal and the direction is opposite.

Second, the movement of particles (2)-curve motion gravity

1) flat throwing motion

1. horizontal velocity Vx= Vo 2. Vertical speed Vy=gt.

3. horizontal displacement Sx= Vot 4. Vertical displacement (sy) = gt 2/2.

5. Exercise time t=(2Sy/g) 1/2 (usually expressed as (2h/g) 1/2).

6. Closing speed vt = (VX 2+vy 2)1/2 = [VO 2+(gt) 2]1/2.

The angle β between the closing speed direction and the horizontal plane: tgβ = vy/VX = gt/vo.

7. Synthetic displacement S = (SX 2+SY 2) 1/2,

The included angle α between the displacement direction and the horizontal plane: tgα = sy/sx = gt/2vo.

Note: (1) Flat throwing motion is a curve motion with uniform change, with acceleration of g, which can usually be regarded as the synthesis of uniform linear motion in horizontal direction and free falling motion in vertical direction. (2) The movement time is determined by the falling height h(Sy) and has nothing to do with the horizontal throwing speed. (3) The relationship between θ and β is tgβ=2tgα. (4) Time t is the key to solving the problem of flat throwing. (5) An object moving along a curve must have acceleration. When the direction of velocity and the direction of resultant force (acceleration) are not in a straight line, the object moves in a curve.

2) Uniform circular motion

1. linear velocity V=s/t=2πR/T 2. Angular velocity ω = φ/t = 2π/t = 2π f.

3. centripetal acceleration a = v 2/r = ω 2r = (2π/t) 2R4. Centripetal force fcenter = mv 2/r = mω 2 * r = m (2π/t) 2 * r.

5. Period and frequency T= 1/f 6. The relationship between angular velocity and linear velocity v = ω r.

7. The relationship between angular velocity and rotational speed ω=2πn (frequency and rotational speed have the same meaning here).

8. Main physical quantities and units: arc length (s), meter (m), angle (φ), radian (rad), frequency (f) and Hz.

Period (t): second (s) speed (n): r/s radius (r): m (m) linear speed (v): m/s.

Angular velocity (ω): rad/s centripetal acceleration: m/s2.

Note: (1) The centripetal force can be provided by a specific force, resultant force or component force, and the direction is always perpendicular to the speed direction. (2) The centripetal force of an object in uniform circular motion is equal to the resultant force. The centripetal force only changes the direction of the speed, but does not change the size of the speed, so the kinetic energy of the object remains unchanged, but the momentum is constantly changing.

3) Gravity

1. Kepler's third law T2/R3 = k (= 4π 2/GM) R: orbital radius t: period k: constant (independent of planetary mass).

2. The law of universal gravitation F = GM1m2/R2G = 6.67×10-1n? The m 2/kg 2 direction is on their line.

3. Gravity and acceleration of gravity on celestial bodies GMM/r 2 = mg g = GM/r 2 r: celestial body radius (m)

4. Orbital velocity, angular velocity and period of the satellite V = (GM/R)1/2ω = (GM/R3)1/2t = 2π (R3/GM)1/2.

5. The first (second and third) cosmic velocity V 1=(g and r)1/2 = 7.9 km/SV2 =1.2 km/SV3 =16.7 km/s.

6. Geosynchronous satellite GMM/(r+h) 2 = m * 4π 2 (r+h)/T2H ≈ 3.6 km h: the height from the earth's surface.

Note: (1) The centripetal force required for celestial motion is provided by gravity, and f center =F million. (2) The mass density of celestial bodies can be estimated by applying the law of universal gravitation. (3) Geosynchronous satellites can only run over the equator, and the running period is the same as the earth rotation period. (4) When the orbit radius of the satellite decreases, the potential energy decreases, the kinetic energy increases, the speed increases and the period decreases. (5) The maximum circling speed and minimum launching speed of the Earth satellite are 7.9 km/s. ..

mechanical energy

work

(1) Two conditions for doing work: the force acting on an object.

The distance that an object passes in the direction of the tunnel.

(2) The magnitude of work: W=Fscosa Work is the unit of scalar work: Joule (J)

1J= 1N*m

When 0

When a= pie /2 w=0 (cos pie /2=0) F does not work.

Dangpai /2

(3) The solution of the overall work:

W total = w 1+w2+w3 ... well-nourished.

W total =F plus Scosa

2. Strength

(1) Definition: the ratio of the work to the time taken to complete it.

Power is the scalar unit of power: Watt (W)

This formula is the average power.

1w = 1J/s 1000 w = 1kw

(2) Another expression of power: P=Fvcosa

When f and v are in the same direction, P=Fv. (at this time, cos0 degree = 1).

This formula can be used to calculate the average power and instantaneous power.

1) average power: when v is the average speed,

2) instantaneous power: instantaneous speed when v is t.

(3) Rated power: refers to the maximum output power when the machine works normally.

Actual power: refers to the output power of the machine in actual work.

During normal operation: actual power ≤ rated power.

(4) Locomotive motion problem (premise: resistance F remains unchanged)

P=Fv F=ma+f (from Newton's second law)

There are two modes of car starting.

1) The car starts at constant power (A decreases until 0).

The p constant v is increasing and f is decreasing, especially f = ma+f.

When f decreases =f, v has a maximum value at this time.

2) The car moves at a constant acceleration (A starts to be constant and gradually decreases to 0).

A is constant, F is constant (F = MA+F), V is increasing, and P is gradually increasing to the maximum.

P at this time is rated power, that is, P must be.

The p constant v is increasing and f is decreasing, especially f = ma+f.

When f decreases =f, v has a maximum value at this time.

3. Work and energy

(1) Relationship between work and energy: The process of doing work is the process of energy conversion.

Work is a measure of energy conversion.

(2) The difference between work and energy: energy is a physical quantity determined by the motion state of an object, that is, a process quantity.

Work is a physical quantity related to the state change process of an object, that is, the state quantity.

This is the fundamental difference between work and energy.

4. kinetic energy. theorem of kinetic energy

(1) Definition of kinetic energy: the energy possessed by an object due to its motion. It is represented by Ek.

The expression ek = 1/2mv 2 can be a scalar or a process quantity.

Unit: joule (j)1kg * m 2/s 2 =1j.

(2) The content of kinetic energy theorem: the work done by external force is equal to the change of kinetic energy of an object.

The expression w = Δ ek =1/2mv2-1/2mv02.

Scope of application: constant force work, variable force work, segmented work and full work.

5. Gravity potential energy

(1) Definition: The energy that an object has because it is lifted. Use Ep to express.

The expression Ep=mgh is a scalar unit: joule (j)

(2) the relationship between gravitational work and gravitational potential energy

W weight =-δ EP

The change of gravitational potential energy is measured by gravity doing work.

(3) The characteristics of gravity work: it is only related to the initial and final position, and has nothing to do with the motion path of the object.

The potential energy of gravity is relative and related to the datum plane, generally taking the ground as the datum plane.

The change of gravitational potential energy is absolute and has nothing to do with the reference plane.

(4) Elastic potential energy: the energy possessed by an object due to deformation.

Elastic potential energy exists in an object with elastic deformation, which is related to the size of deformation.

The change of elastic potential energy is measured by elastic work.

6. Law of Conservation of Mechanical Energy

(1) mechanical energy: kinetic energy, gravitational potential energy and elastic potential energy.

Total mechanical energy: E=Ek+Ep is scalar and relative.

The change of mechanical energy is equal to work without gravity (such as work done by resistance)

Δ δE = W Non-weight

Mechanical energy can be transformed into each other.

(2) Law of Conservation of Mechanical Energy: The kinetic energy and gravitational potential energy of an object only when gravity does work.

Mutual transformation occurs, but the mechanical energy remains unchanged.

Expression: Ek 1+Ep 1=Ek2+Ep2. Only gravity works.