Chapter 3 Tides Solutions

(ii) This leads to accumulation of sea water over a long period of time leading to formation of swamps & marshes.

(iii) The tides help in maintaining the mangroves and the coastal biodiversity here.

(iv) Certain areas near the sea coast being low lying & waters being shallow also lead to sediment deposition by sea waves leading to formation of lagoons.

(v) In this way, at some places along the coast, the low lying areas turn into lagoons or marshy lands.

(ii) When a place (meridian) faces the moon the gravitational force of the moon exceeds the centrifugal force of the earth leading to high tide here as the water is pulled towards the moon.

(iii) At the same time the place on the earth located at the opposite meridian to the place experiencing high tide, the centrifugal force of the earth exceeds the gravitational force of the moon. Thus, the water is pulled in the direction away from the moon leading to high tide.

(iv) The water required for the high tide moves in from places that are at right angles to those having high tides causing a low tide at those places.

(v) Thus, place located on the opposite meridian to the place experiencing high or low tide will also experience high or low tide respectively.

3. Answer in brief:

4. In what way will the following depend on the tides:

5. Observe figure of neap tide and answer the following questions:

Question 1.
Which phase of the moon does it show?
Answer:
The diagram shows the phase of the quarter moon.

6. Differentiate between:

7. Describe the positive and negative effects of tides:
Answer:
The positive effects of tides are as follows:

The negative effects of tides are as follows:

Activities:

Class 7 Geography Chapter 3 Tides InText Questions and Answers

Differentiate between:

Write short notes:

(ii) Hence, the tide on these days is much higher than the average high tide.

(iii) This is known as spring tide.

(ii) This position occurs on the first and third quarter of each month. On both these days the forces of both the sun & the moon operate at right angles on the earth.

(iii) At the places where the sun causes high tide, the gravitational pull of the moon which is at right angles also acts on the water.

(iv) Due to such conditions the water level rise is less than usual at the time of high tide. Similarly, fall in water level is less than usual at the time of low tide.

(v) Such tides are called neap tides.

(ii) The vertical distance between a crest and the following trough is called the amplitude of the wave whereas the distance between two successive crests or troughs is called wave length.

(iii) The wave length, its amplitude & its velocity depend on the velocity of the wind.

Formative Assessment:
Observe the activity on pages 9, 10 of the textbook & discuss the result of the activities and answer the question given below:

Can you tell?
Answer the following of questions with the help of figure

Question 1.
How do the tides occur?
Answer:
Tides occur due to the relative positions of the moon, the sun, and the earth.

Class 7 Geography Chapter 3 Tides Additional Important Questions and Answers

Fill in the blanks choosing the correct options from the brackets:

Match the following:

‘A’

‘B’

(1)  Bay of Fundy
(2)  Gulf of Khambhat
(3)  Open Seas
(4)  Peninsular India

(a)  1100 cm
(b)  100 -150 cm
(c)  1600 cm
(d)  30 cm

Name the following:

Define the following:

Write whether the following statements are true or false:

Give geographical reasons:

Answer in brief:

Draw a neat labelled diagram of:

Observe the following pictures and answer the following questions given below and discuss:


Question 1.
Do the above photographs show the same place or different places?
Answer:
Both the photographs show the same place.

Try this:

Take a wide open large dish.
Keep the dish on a table or a flat surface.
Fill water in the dish up to the rim,(we have to generate waves in the dish).