NCERT Solutions for Class 4 Mathematics Unit-8 Carts And Wheels

NCERT Textbook Page 81
1.You must have seen many such round things around you. List some more in your notebook.
Ans. List of some round things around me
(a) Bangles                  (b) Bread       (c) Glass                  (d) Tawa
(e) Pressure cooker   (f) Bowl          (g) Wheel chair      (h) Coins
(i) Drum                      (j) Tyre           (k) Cup                     (l) Plate
(m) Moon                   (n) Sun           (o) Globe                  (P) Ball.

NCERT Textbook Page 82
1. Have you ever gone to a bangle shop?
Ans. Yes, I went to a bangle shop with my mom.

2. Guess which of these bangles is of your size?
Ans. The smallest bangle.

3. Take a wire and make a bangle for yourself. Can your teacher wear this bangle?
Ans. I made a bangle by wrapping it around a pipe. I showed this to teacher, she cannot wear this. ‘ ”

4. A bangle can be used to trace a circle. What are the other things around you that you can use to trace a circle?
Ans. There are so many things around us, which can be used to trace a circle.
Such as coins, bowl, plate, glass, the cycle rim, etc.

5. Trace a circle with the help of some of these in your notebook or on the ground.
Ans.

•Which thing makes the smallest circle ?
Ans. Coin makes the smallest circle.
• Which thing makes the biggest circle?
Ans. Glass makes the biggest circle.

NCERT Textbook Page 83
Games with Circles
1.Do you play these games?
Ans. I do play these games.

2. Which song do you sing when you play these?
Ans. There are so many songs which we sing while playing these games.
One of them is “Rain-rain go away, come again another day We children want to play Rain-rain go away”.

3. Why do we make a circle in each of these games?
Ans. Because a circle has no corner. And every children stand at the circle gets equal importance and opportunity.

4. What if a rectangle was made? Discuss.
Ans. Although, some games are played by making rectangles.
But some games such as cricket require a circle. If a rectangle is made in cricket, the distance of boundary from the players will, become unequal

5. Think of some other games you play by making circles.
Ans. Some games which are played by making circles are – Musical chair race, Passing a parcel, etc.

NCER.T Textbook Page 84
Making a Circle
1. Is any of these a good drawing of a circle?
Ans. No, none is a good drawing of a circle.

2. Can you draw a circle on the floor with a chalk? Try.
Ans. Yes I can draw a circle on the floor using a chalk.
One of them is here

3. Also draw a circle in your notebook using a pencil.
Ans. The circle drawn in the notebook using a pencil is given here.

4. Look at the circles drawn by your friends. Who has drawn the best circle?
Ans. Circles drawn by some of my friends are given here
The circle drawn by Molu is the best.

NCERT Textbook Pages 85-86
Making a Circle with a Rope
1. Do the activity in small groups. Each group should take a rope of a different length. See the circles made by different groups. Which group made the smallest circle?
Ans.

Circle drawn by Raja’s group is the smallest circle.

2. How long was their rope?
Ans.

3. Does a longer rope make a bigger circle?
Ans. Yes.

4. Can you say why?
Ans. Longer rope act as a bigger radius, so circle made by longest rope was biggest.

5. What was the radius of the smallest circle?
Ans. The radius of smallest circle was 2 metre.

6. Draw the radius of this bangle using a ruler. Measure the length of the radius.
Ans. The length of radius = 1 inch.

7. Now see what your friends have drawn. Discuss the length of the radius they measured. Is it the same as yours?
Ans. The radius drawn by all of my friends for the given circle is same.

8. Draw the radius of these circles. Guess which circle has the longer radius
Ans.

The radius of bigger circle is longer.

9. Measure the radius of both circles using a ruler.
Write the length of their radius.
(a) Radius of the green circle______
(b) Radius of the blue circle ______ 
Ans.
(a) Radius of the green circle     (A) is 1 cm.
(b) Radius of the blue circle      (B) is 2 cm.

Find Out
1. Measure the radius of the wheels of a bicycle or a bullock-cart. You can use a thread or a measuring tape. .
Ans. The radius of the wheels of a bicycle is 12 inches. The radius of the wheel of a bullock cart is 20 inches.

2. Are all the wheels of a bicycle or a bullock-cart of the same radius?
Ans. Yes, all the wheels of a bicycle or a bullock cart are of the same radius.

3. Have you seen a tractor or a road roller?
Ans. I have seen tractor and road roller both.

4. Which is the biggest wheel you have ever seen?
Ans. The wheel of a merry-go-round is the biggest wheel I have ever seen.

5. Are all wheels of a tractor or road roller of the same radius?
Ans. No, all wheels of a tractor or a road roller are not of the same radius. Their back wheels are bigger.

6. Lali and Kali are tied to a pole with ropes. Kali has a longer rope. Who can look for more grass to eat?
Ans. As Kali has a longer rope, so she can look for more grass to eat.

NCERT Textbook Page 88
Using a Compass
1. Have you seen a compass before? How will you use this to make a circle?
— Open your compass.
— Press the tip of the compass on the paper. Hold the compass from the top. — Without moving the tip, try to move the pencil around.
— Do you get a circle?
Ans. Yes, by doing this I got a circle drawn.

2. Is this circle better than the one you made earlier without a compass? Draw the radius of this circle and measure it.
Ans. Yes, this circle is better than one I made earlier without compass.
The radius of the circle is 4 centimetre.

3. Now you can make your own designs like Daljeet had made. How many did you make?
Ans.I can make several designs. Some of them given here

4. Guess how this design has made. Use a compass to make similar one in the box

Ans. This design can be made by using a compass like this

NCERT Textbook Page 89
5. Why did Naina get such a drawing? Discuss.
Ans. Naina did not put the point of her compass again on the same place before going to find an eraser. So, she got such design.

6. Can a circle have more than one centre?
Ans. No, a circle has only one centre.

7. Did any one of you ever get a shape like Naina’s?
Ans. Yes, so many times. When I draw a circle using more than one centres.

NCERT Textbook Page 91
1. Now you trace a circle on a paper using a bangle. Cut it. Then find its centre like Sameena did.
Ans. After tracing the circle using a bangle on notebook, cut the circle from its outline. Fold the circle into half.
Fold it again in half. Open the folded circle. The crossing point of the two creased line is its centre.

NCER.T Textbook Page 92
1. Can you balance a plate on your finger?
Ans. No, I cannot balance a plate on my finger. It is very difficult. It requires a lot of practice.

2. You also try to balance a plate or a round lid on your finger. Where does it balance?
Ans. The balance of a plate or a round lid is at its centre.

NCERT Textbook Page 93
Guess
Now everybody was excited to spin their tops which looked like this.

1. Whose top will not spin at all?
Ans. The top made by Zakir and Naina will not spin at all.

2. Whose top will spin a little?
Ans. Guddo’s top will spin a little.

3. Whose top will spin the best?
Ans. Appu’s top will spin the best.

4. In whose top is the stick nearest to the centre?
Ans. In Appu’s top the stick is nearest to the centre.
Make Your Own Top

5. To make the top spin well, where will you make the hole?
Ans. I will make the hole at the centre to make the top spin well.