Estimates commonly used in junior high school physics

50 grams of one egg.

A person is meters tall.

A person weighs 50 kg.

The flagpole is 12 meters high.

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Estimation of Common Physical Quantities Learning Situation Analysis: Through recent review questions, it is found that students have certain difficulties in estimating and judging some common physical quantities. It seriously affects the correct calculation and judgment of the laws of physical phenomena.

Therefore, today we are going to further review the basis judgment of common physical quantities such as length, velocity, time, area, mass, volume, force, pressure, current, voltage, electric power, temperature, etc. Learning Focus: Through the observation and understanding of some common sense, you can make basic and correct judgments on some common physical quantities.

Learning difficulties: Truly let students know physics, understand physics, apply physics Listening and writing 1. The concept of speed: formulas, units, and unit conversion; The physical meaning of the unit.

2. The concept and unit of mass, 3. The concept, formula, unit, and meaning of pressure.

Measuring instruments to be estimated in junior high school physics:

1. a scale.

2. Spiral micrometer (micrometer).

3. An ammeter with a range of 0-3A and a voltmeter with a range of 0-3V.

4. Spring dynamometer with a minimum scale.

5. Mercury barometer.

Upstairs, vernier calipers also need to be estimated!

In the current junior high school physics, with regard to the use of measuring instruments, only length measurement has a clear requirement, and it is necessary to estimate the next digit of the graduation value.

Other instruments are generally only used with the closest scale value (including the graduation value).

A bottle of ordinary mineral water should be about 500ml, and the mass should be greater than 500g

c. Generally, the volume of the thermos flask is 2L

The diameter of the d atom is less than 1 nm

Flipping the book + memorizing, it shouldn't be bad (right).

I am a candidate for the third year of junior high school in Shanghai, and I hope good luck!

The mass of an average middle school student: 60kg

A student stands under the national flag and estimates the height of the flag: measure it with a ruler and multiply it by a multiple (similar questions are also done using the comparative method).

The current when a household incandescent lamp (TV, flashlight, etc.) glows:

The quality of a normal newborn baby:

08 Exam questions in a certain district of Shanghai, I think it is more difficult, I may not take the test] The moon orbits the sun for one time, which takes about 28 days.

The normal body temperature of a person is: 37°C

The closest thing to a kilogram of the following objects is———c)a) a one-dollar coin.

b) One ordinary egg.

c) water. d) A secondary school student.

A junior high school student, the area of the sole of one foot is 200 square centimeters, and the pressure of the foot on the ground when he stands on one foot is about: 20,000pa (similar questions are all in Wanpa, remember that walking is the area of one foot soles, and when standing, the area of the soles of two feet is counted).

The closest normal electricity consumption in a month: 60 kWh.

Normally, the temperature at which a person feels comfortable is around 25°C

A glass of boiling water is ready to drink from just arrival, and the calories released are about: 50,000 joules.

Which object is subjected to gravity of about 1 N: a pack of instant noodles (I Khan - a Passat sedan (=.)

Is this an advertisement? ) the highest height is the closest: meters.

a. The walking speed of ordinary adults is generally about Kaizao s, and it does not reach 5m s; It does not fit the theme of rock filial piety

b. The water temperature suitable for people to take a bath is 40, which is not in line with the topic;

c. The quality of a ninth-grade physics textbook is about half a catty (i.e., about 250g); off-topic;

d. The height of the classroom door is about 2m, which is in line with the topic

Therefore, choose D

A person's normal body temperature is about 37, a person's weight is about 450N, the walking speed is about 1m s, and the pulse is about 70 minutes, so it is obviously unreasonable to talk about A.