Physics, help me pull, physics problems help help pull

In winter mornings, a layer of small water droplets often appear on the surface of the glass, please explain why there are small water droplets?

Answer: Due to the large temperature difference between indoor and outdoor in winter, the indoor hot air liquefies when it encounters cold glass and forms water droplets. Water droplets form on the glass in the room.

In the summer, when the weather is very hot, a layer of small water droplets will appear on the glass in the room with the air conditioner turned on, please explain why these small water droplets appear? Is it on the outside or inside of the glass?

Answer: Due to the air conditioner, the temperature difference between indoor and outdoor is formed, and the hot air outside the outdoor meets the cold glass and forms water droplets on the outdoor glass.

1.In winter, there is a large temperature difference between indoor and outdoor temperatures, so water droplets are generated.

2.Because the outside air is hot in the summer and the room temperature of the air conditioner is relatively low, the hot water vapor liquefies into small water droplets when it hits the cold glass, so it is attached to the glass! It is the outside of the glass. It should be right!

Junior high school physics questions.

This is a vaporization problem due to the temperature difference:

In winter, the indoor temperature is higher than the outdoor temperature, and when the indoor gas encounters the glass, the "condensation" reaction occurs due to the low temperature, and it becomes water droplets inside the glass.

The same is true in summer, the problem of temperature difference, condensation.

There is also a solid-to-liquid called "liquefaction", liquid-to-gas is called "vaporization", and there is a non-removal, specifically to check the junior high school physics book...

The water vapor in the air liquefies into small water droplets when it is cold, and it will appear in winter and summer, and in summer, the air-conditioned room is outside, and there are small water droplets on the glass.

The propagation speed of the sound in the air is 340m seconds, and after four seconds, the echo is heard, and the sound has traveled a total of 340*4=1360 meters, and in four seconds, the car has traveled another 10*4=40 meters, so the distance from the mountain when the car hears the sound is: (1360-40) 2=660 meters.

1. Lightning and thunder are generated at the same time, the propagation time of light is negligible, and the distance of sound propagation within 5s is s = 340 5 m = 1700 m

Therefore, Xiaohong is about 1,700 meters away from where the lightning occurs.

2. Seconds: The distance that sound travels in water is 1500 m = 1200 m, and the water depth is 1200 2 m = 600 m because the sound travels back and forth

Solution 1: Ignore the propagation time of light Xiaohong is s=vt-340*5=1700 meters from the place where lightning occurs.

Second, the sound is heard for a second and then an echo is received, indicating that the sound reaches the bottom of the river in seconds, so the water depth is.

h=vt=1500*m.

(1) Heat absorbed by water:

q suction = cm (t-t) = 4200 j (kg) kg (18 12 ) 2016j

2) Excluding heat loss, the heat emitted by lead: q release q absorption 2016jq release = cm (t -t).

2016j= c× (98 ℃－18 ℃c= 126j/(kg•℃)

Dear, this is calculated directly according to the formula.

One minute hand revolution is 1 hour, i.e. 3600s, 1 2 t 2 3600s 1800s

The second hand is 1 minute in the week, i.e. 60s, 2 2 t, 2 60s, 30s, so, 1: 2, 1800s: 30s

v r So: v1:v2 r1 1:r2 2 2 1:3 60

Basic knowledge of circular motion:

One turn of the minute hand is 3600s, 1 2 t 2 3600s 1800s

The second hand turns 60s, 2 2 t 2 60s 30s, so, 1: 2 1800s: 30s 1: 60v r

So: v1:v2 r1 1:r2 2 2 1:3 60 1:90

1. Relative motion; Hinder.

2. Roughness; the larger; Pressure; the larger;

3. a straight line at a constant speed; Pulling force; two-force balance; Friction; Friction;

1. No change. 2. Inertia; ground resistance; Less resistance.

30；Left.

East; Get bigger.

Vertically upward; Unchanged 5

Hasten; 5

According to Figure A, when the ambient temperature is 10, RT=500 U=I*R=

In the circuit, the minimum value of resistance r=u i=6

rt+r>300ω

rt>100ω

According to Figure B, the maximum ambient temperature for normal operation is 50

tat, sorry, I can't do anything, you can.