Using air from mouth in Air, Winds And Cyclones – Class 7 Science Experiment
Chapter Name: Air, Winds And Cyclones
Activity Name: Using air from mouth in Air, Winds And Cyclones
Activity Description:
This activity involves two experiments related to the behavior of air and its pressure. In the first experiment, a glass containing water is used with two straws placed inside it. One straw is submerged in the water, and the other is placed horizontally.
When air is blown through the horizontal straw, the water inside the glass reacts in a certain way. The second experiment involves placing a cotton ball just inside the mouth of an empty bottle and attempting to blow air to make the ball enter the bottle.
This activity can be performed with bottles of different sizes to observe the results.
Required Items:
- Glass containing water
- Two straws
- Empty bottle(s)
- Cotton ball(s)
Step by Step Procedure:
Experiment 1:
- Fill a glass with water.
- Insert one straw vertically into the water, ensuring it is submerged.
- Place the other straw horizontally just above the water’s surface.
- Blow through the horizontal straw and observe what happens to the water.
Experiment 2:
- Take an empty bottle and place it on a table.
- Put a cotton ball just inside the mouth of the bottle.
- Attempt to blow air onto the cotton ball and make it enter the bottle.
- Try the same activity with bottles of different sizes.
Experiment Observations:
Experiment 1:
- The water in the glass may splash or move when air is blown through the horizontal straw.
Experiment 2:
- The cotton ball may enter the bottle when air is blown onto it.
Precautions:
- Take care while blowing through the straws to avoid any splashing or spills.
- Ensure the cotton ball is placed safely, and do not blow with excessive force.
Lesson Learnt from Experiment:
The activity demonstrates the principles of air pressure and its effects on liquids. Blowing through the horizontal straw creates low pressure inside the straw, causing water to rise inside it due to higher pressure in the glass.
Similarly, blowing air onto the cotton ball reduces the pressure above it, allowing it to be pushed into the bottle by the higher pressure outside.
