Whether there are dependencies between variables in the following processes, among which those are functional relationships (1) the relationship between the distance and time during the earth's revolution around the sun (2) the relationship between the height of the shot put from the ground and time when it is inclined in the air (3) the relationship between the water level recorded at a hydrological observation point and time (4) an intersection, Through the relationship between the number of cars and time

Whether there are dependencies between variables in the following processes, among which those are functional relationships (1) the relationship between the distance and time during the earth's revolution around the sun (2) the relationship between the height of the shot put from the ground and time when it is inclined in the air (3) the relationship between the water level recorded at a hydrological observation point and time (4) an intersection, Through the relationship between the number of cars and time

(1) And (2) make it clear that after the initial conditions are determined, each time corresponds to the determined distance or height, which is both a dependency and a functional relationship
(3) And (4) are not very clear. Each time point will correspond to one (and only one) water level or number of vehicles, so it is a functional relationship. However, only knowing the time can not predict the water level or number of vehicles, which I don't think is a dependency

A general method to judge whether two variables constitute a functional relationship. Thank you,

If a variable belonging to set a has a uniquely determined value corresponding to it in set B according to the corresponding relationship f (x), but if it is not uniquely determined, it does not constitute a functional relationship. If several elements in set a correspond to an element in set B, it also constitutes a functional relationship

Is there a definite dependency between the two variables during the following changes? If yes, please write the function expression (1) The circumference C (CM) of the square changes with the side length a (CM) (2) The area s (cm ^ 2) of a circle changes with the radius R (CM) (3) The circumference of a rectangle is 20cm, and its length y (CM) changes with the width x (CM) (4) The unit price of an exercise book is 0.5 yuan. The total price of S (yuan) for purchasing n exercise books changes with the number of n (copies) purchased Add bonus points according to the answer time! Add 20 in the first half hour

Both are (1) the perimeter C (CM) of a square changes with the side length a (CM). C = 4A (2) the area s (cm ^ 2) of a circle changes with the radius R (CM). S = π R ^ 2 (3) the perimeter of a rectangle is 20cm, and its length y (CM) changes with the width x (CM). Y = 10-x (4) a practice

Judge whether there is a dependency between the two variables in the following questions, point out which variable is an independent variable, and say which quantity is a function of the other quantity Xiao Ming's height and age Xiao Jie's weight and age Mathematics score and student number in mid-term examination Tomorrow's temperature predicted by the meteorological observatory and the city The seat number in the cinema is the same as the ticket number in the audience's hand

Xiao Ming's height and age: age is an independent variable and height is a dependent variable
Xiao Jie's weight and age: age is an independent variable and weight is a dependent variable
The math score of the mid-term examination has nothing to do with the student number
Tomorrow's temperature and city predicted by the Meteorological Observatory: temperature is an independent variable and city is a dependent variable
The seat number in the cinema and the ticket number in the hands of the audience: the seat number is an independent variable and the ticket number is a dependent variable

Demand function supply function Let demand function QD = f (x): Price demand 6 yuan 2000 4 yuan 4000 2 yuan 6000 Supply function QS = f (x): Price supply 5 yuan 7000 3 yuan 5000 1 yuan 3000 Seeking equilibrium output and equilibrium price

QD = f (x) = a-bxx = 6, QD = 2000, a-6b = 2000x = 4, QD = 4000, a-4b = 4000, so B = 1000, a = 8000, QD = 8000-1000xqs = f (x) = C + DXX = 5, QS = 7000, C + 5D = 7000x = 3, QS = 5000, C + 3D = 5000, so d = 1000, C = 2000, QS = 2000 + 1000x equilibrium, that is, QS = QD, so 8000-1000x

It is known that the demand function of a product is Q1 = 60-2p and the supply function is Q2 = 30 + 3p. Q. if the government imposes a sales tax of 5 yuan per unit of product, what will the government do What is the tax revenue? Among them, how much do producers and consumers bear/

Equilibrium without tax Q1 = Q2, 60-2p = 30 + 3P, equilibrium price P = 6, output Q = 48; After the government collects 5 yuan of sales tax, the supply function becomes Q2 = 30 + 3 (P-5) equilibrium output Q1 = q260-2p = 30 + 3p-15p = 9 q = 42 tax revenue = 42 * 5 = 210 borne by consumers (9-6) * 42 = 126 borne by manufacturers [6 - (9-5)