NCERT Class VII Science Solutions: Chapter 8-Winds, Storms and Cyclones Part 3

Download PDF of This Page (Size: 382K)

Question 11:

To expel hot air out of the kitchen, ‘A’ has an exhaust fan fitted on the window of her kitchen and ‘B’ has a similar exhaust fan fitted on the wall near the ceiling of her kitchen. Which of the exhaust fan will expel the hot air more effectively? Explain why?

Answer:

B’s exhaust fan will expel the hot air more effectively because hot air rises up and her fan is at greater height than A’s.

Question 12:

Why is it advisable not to shut all the doors and windows during a storm?

Answer:

To avoid the roof getting blown away due to the low pressure created by heavy wind.

Image of what is storm

What is Storm

Image of what is storm

Question 13:

A flat in Mumbai with a balcony facing the sea has some clothes hung on a clothes line in the balcony. Towards which direction the clothes will be blown in the afternoon? Explain.

Answer:

The clothes will be blown towards the house due to sea breeze blowing towards the land.

Question 14:

Figure shows a diagrammatic representation of trees in the afternoon along a sea coast. State on which side is the sea: A or B? Give reasons for your choice.

As showing in images is a trees

Trees

As showing in images is a trees

Answer:

B as the wind is blowing from the sea to the land.

Question 15:

A flag mounted on a flag post near the sea coast flutters in the direction of sea. At what time of the day does this happen – at midnight or in the afternoon?

Answer:

At night, the water cools down more slowly than the land. So, at mid – night, cool wind from the land moves towards the sea. Therefore, at mid – night the flag mounted on a flag post near the sea, coast flutters in the direction of sea.

SHORT ANSWER QUESTIONS

Question 16:

Match Column I with Column II. There can be more than one match.

Match Column I with Column II. (Q)
Match Column I with Column II. (Q)

Column I

Column II

On heating air

Descends

On cooling air

Expands

Contracts

Rises

Answer:

Match Column I with Column II. (A)
Match Column I with Column II. (A)

Column I

Column II

On heating air

ii Expands

iv Rises

On cooling air

i Descends

iii Contracts

Question 17:

Paheli kept an empty bottle made of plastic inside a refrigerator. After few hours, when she opened the refrigerator she found the bottle had collapsed. Explain the possible reason.

Answer:

The air inside the bottle contracts due to low temperature hence the bottle collapses due to the outside pressure.