Activity 8.8:
Aim: To show that air exerts pressure.
Instruction
1. Fill a glass with water until it is full.
2. Cover the mouth of the glass with a card.
3. Hold the card and turn the glass upside down quickly.
4. Remove your hand slowly. Observe if the water flows out (Figure 8.34).
![](http://pt3science.blog.onlinetuition.com.my/wp-content/uploads/sites/21/2023/09/F2C8_18-300x291.jpg)
Question
Why doesn’t the water flow out when the hand that presses the card is removed?
Answer:
This is because the atmospheric pressure acting on the card is strong enough to support the weight of the water in the glass.
Aim: To show that air exerts pressure.
Instruction
1. Fill a glass with water until it is full.
2. Cover the mouth of the glass with a card.
3. Hold the card and turn the glass upside down quickly.
4. Remove your hand slowly. Observe if the water flows out (Figure 8.34).
![](http://pt3science.blog.onlinetuition.com.my/wp-content/uploads/sites/21/2023/09/F2C8_18-300x291.jpg)
Question
Why doesn’t the water flow out when the hand that presses the card is removed?
Answer:
This is because the atmospheric pressure acting on the card is strong enough to support the weight of the water in the glass.