englishvstep
Region: VN
Sunday 08 November 2026 11:35:00 GMT
2060
108
3
6
Music
Download
Comments
englishvstep :
All right. Today's lecture is about heat. Actually, we will talk about the ways heat moves. This is called heat transfer. Now, there are three types of heat transfer. They are called [slowly] convection..., conduction..., and... radiation. OK? OK! Convection happens when heat moves through gases and liquids. When air or water heat up, they get lighter. Then they move away from the heat. They rise. When they get cooler, they change direction. They come back down to the heat again. In convection, this repeats over and over. For example, a hot-air balloon. Fire heats the air. The hot air becomes lighter. The balloon rises up. But, as the air cools, it gets heavier. So, the balloon goes down. Convection is how hot-air balloons fly. Now, next is conduction. This happens when heat moves through solids. First, a solid object is put on heat. Eventually the solid object takes this heat and it gets hot. Some materials are very good at conduction. Metals, for example. This is why many cooking pans are made of metal. They heat up quickly. But don't touch them. Ouch! Conduction causes many burns. Finally, heat also moves by radiation. If you can feel heat from an object without touching it then it is radiating heat. Remember you can't see this heat. The sun, a toaster, a dryer. All these things use radiation. Have you ever warmed your hands by a fire? Even this is radiation. OK? Do we understand?
2026-11-08 11:35:13
0
englishvstep :
21 B 22 C 23 D 24 D 25 D
2026-11-08 11:43:31
1
juldyz_detski.massage :
🥰🥰🥰
2026-11-08 12:09:21
0
To see more videos from user @englishvstep4u, please go to the Tikwm
homepage.
