الطاقة: الطاقة الحرارية- الحمل

The video tutorial explains the concept of heat transfer by convection, which occurs in fluids like liquids and gases but not in solids. It demonstrates this process using an experiment with water and sand, showing how heated water rises and cooler water descends, creating a circular motion. The tutorial also discusses how convection occurs in the atmosphere, where the sun heats the Earth's surface, causing the air above it to warm and rise, while cooler air takes its place.

What is the primary medium where convection occurs?

• Vacuum

• Liquids and gases

• Plasma

• Solids

In the water experiment, what causes the water molecules to move upwards?

• Magnetic force

• Gravity

• Heat from the flame

• Electric current

What is observed when sand grains are added to the heated water?

• They form a straight line

• They dissolve

• They move in a circular motion

• They float on the surface

How does the sun contribute to convection in the atmosphere?

• By cooling the Earth's surface

• By heating the Earth's surface

• By creating wind

• By evaporating water

What happens to the air when the Earth's surface heats up?

• It cools down

• It rises and is replaced by cooler air

• It becomes denser

• It remains stationary