A student's climbing speed is 1 m / s and the downhill speed is 3 / s

A student's climbing speed is 1 m / s and the downhill speed is 3 / s

This topic is typical
Average speed = total distance / total time
Let s = downhill distance
Uphill time = s / 1
Downhill time = s / 3
Average speed = total distance / total time = 2S / (uphill + downhill) = 2S / (s / 1 + S / 3) = 1.5m/s
The key to this kind of questions is to grasp the average speed = total distance / total time, and then make different analysis according to different questions

The difference between rate and average rate

1、 Definition: the average speed is the distance (route) in unit time; the average speed is the displacement in unit time (the vector of the first and last positions of the particle in this period of time). [x0d] 2. The speed has only one size, which is a scalar; besides the size, the speed has direction, which is the tangent direction of the trajectory curve, which is a vector

Physics: the difference between velocity and average velocity!

Velocity is a scalar, that is, the value of velocity. Compared with velocity, there is only one direction missing. Mathematically, it is equivalent to the relationship between vector and the module of vector
The average velocity is a vector, and the calculation method is (V initial + V mode) / T

Existing equipment: one battery pack, three switches, two lights, several wires. Please design a circuit to meet the following requirements: when only switch S1 is closed, light L1 will light up; when only switch S2 is closed, light L2 will light up; when only switch S3 is closed, light L1 and L2 will light up; when S1, S2 and S3 are opened and closed, light L1 and L2 can not be closed at the same time

How do you draw it?

Two switches, several wires, one lamp and one electric bell are connected in parallel, which is consistent with closing. When two switches are on, the light bulb will be on and the electric bell will sound. When only one switch is closed, the light bulb will not be on and the electric bell will not ring. When the other switch is closed, the light bulb will light up and the electric bell will not ring. Draw the circuit diagram

{--- light bulb}
{--{---------------}---}
{{-- switch -- bell}}
{ }
{{-- switch -- power supply}}}
Please do not copy
(symbol as wire)
I'm so tired`

There are power supply, switch, wire, two small bulbs, two ammeters, please design a circuit. Requirements: two bulbs in parallel, A1 & nbsp; measure the current of trunk road, A2 measure the current of L1. (1) please draw the circuit diagram in the dotted box of Figure 1; (2) connect the components in Figure 2 according to the circuit diagram. (the current of L1 is about 0.5A, and that of trunk road is about 1a)

(1) According to the meaning of the question, L1 and L2 are connected in parallel, A1 & nbsp; measures the current of the trunk circuit, A2 measures the current of L1, and the switch controls the whole circuit; the circuit diagram is as follows: (2) because the trunk circuit current is 1a, the range of ammeter A1 is 0 ~ 3a, and the current through L1 is about 0.5A, then the range of ammeter A2 is 0 ~ 0.6A

The problem of using V-T image to calculate the car acceleration in Physics
That's the question. There's always a standard. Does it mean to calculate the slope? Is it to take the first and last points, or add up the speed divided by the sum of time, or use a protractor to measure the angle,

The slope is the ratio of V to t
The greater the ratio, the greater the acceleration. So V / T is the slope
You can also simulate the trigonometric function of RT triangle, that is, the larger the ratio of Tan of an angle, the larger the angle, the steeper the acceleration

Why is the image of force and acceleration not the origin in physics

If the force is an external force, it will pass through the origin
F=ma
If the force is not external force, it should be discussed according to the situation
Generally, there is friction in the horizontal direction
So f-f = ma
F = ma + F, so it doesn't pass through the origin

The distance time (S-T) image of uniform linear motion is a The velocity time (V-T) image of a straight line moving at a uniform speed is a straight line
Such as the title

The distance time (S-T) image of uniform linear motion is an inclined line, and the velocity time (V-T) image of uniform linear motion is a line parallel to the time axis

The relationship between distance and time of a moving object is expressed as s = 3T (m). Please draw the speed time image of the object in the figure

Constant speed
It's a straight line