Practicing with Our Wondrous World Class 4 Solutions Chapter 7 How Things Work Class 4 Questions and Answers improves a student’s confidence in the subject.
Class 4 EVS Chapter 7 How Things Work Question Answer
How Things Work Class 4 EVS Question Answer
Our Wondrous World Class 4 EVS Chapter 7 Question Answer – Class 4 EVS How Things Work Question Answer
Activity 1 Page 105
Question 1.
Do you think all objects can spin? Make a list of a few objects that can spin.
Answer:
No, not all objects can spin. Only certain shapes and designs help an object spin easily. List of a few objects that can spin are -Coin, Bangles, Wooden top (spinner), Ceiling fan, Pottery wheel and Frisbee.
Question 2.
Collect the objects mentioned in the table given below. Spin and observe them. Then, complete the table.
Answer:
| Objects | I observe | I wonder | |
| Coin | As it slows down, it begins to shake | Why does it start to shake as it slows down? | Maybe because it loses balance and speed. |
| Bangle | As time passes, the sound becomes louder | Why does the sound change while spinning? | Because it is spinning slower. |
| Pencil | It does not spin properly; it falls quickly | Why doesn’t it spin like a coin? | Because it is not round and is uneven. |
| Piece of Stone | It doesn’t spin; it just falls over | Why can’t a stone spin? | Because it has an irregular shape. |
| Wooden Spinner (Top) | Spins smoothly and stays upright for some time | How does it balance while spinning? | Its pointed tip and round body help balance. |
| Eraser | It does not spin; it just wobbles and stops | Why doesn’t the eraser spin? | It is soft and not shaped to spin. |
Activity 2 Page 106-107
Question 1.
Collect things, such as pieces of cardboard, toothpicks, an empty tube of a ballpoint pen, and other small objects. Make the following spinners. Spin them and record your observations.
Answer:
Discuss Page 108
Question 1.
Which of the spinners did not spin properly? Discuss the possible reasons.
Answer:
The spinner with the toothpick away from the centre did not spin properly.
This is because
- The hole was not at the centre, so it was unbalanced.
- Because it was not balanced, it wobbled and fell down quickly.
- The sides were not equal, so it could not spin nicely.
Question 2.
Have you noticed the position of the hole in the first two spinners? Did this difference in the position of the hole make a difference in the spinning of these spinners?
Answer:
Yes! The position of the hole made a big difference. When the hole was at the centre, the spinner spun smoothly and stayed straight. When the hole was away from the centre, the spinner did not spin well and fell down.
Activity 3 Page 110-111
Question 1.
Collect objects, such as a leaf, an iron nail, an empty bowl (katori), a plastic bottle with a lid, pieces of stone, aluminium foil and other things of your choice. Fill a bucket with water. Before dropping the things listed in the table, guess whether things will float or sink. You may try other things too. Then,observe what happens when it is actually dropped in water. You can write ‘F’ for objects that float and ‘S’ for objects that sink.
Answer:
Discuss Page 111
Question 1.
Did all the light objects float and all the heavy objects sink? Name the heavy objects that floated and lighter objects that sank.
Answer:
No! Not all light objects floated and not all heavy objects sank.
Heavy objects that floated
- Empty steel bowl (It is heavy but floated because it is hollow from inside.)
- Empty bottle with a closed lid (Even if it is a little heavy, it floated because of air inside.)
Light objects that sank
- Some small iron nails or pins are light, but they sank because they are made of heavy metal.
Activity 4 Page 112
Question 1.
Let us find out whether shape plays a role in floating and sinking.
Answer:
| Aluminium foil when | Before dropping (What is your guess?) |
Before dropping (Why do you think so?) |
After dropping (What is your observation) | After dropping (What could be the reason?) |
| Spread out | Float | It covers a larger surface area, so it can hold air and stay on top. | Floats | Large surface area and trapped air keep it afloat. |
| Pressed tightly into a ball | Sink | It becomes dense and small, so it cannot trap much air. | Sinks | Higher density and less air trapped inside. |
| In a cup-like shape | Float | It can trap air inside, helping it float like a boat. | Floats | Air trapped inside acts like a buoyant force to keep it a float. |
Activity 5 Page 113-114
Question 1.
Let us create some boats
Answer:
- Collect some paper, cardboard boxes, ice-cream sticks, clay, adhesive tape, etc.
- Create groups of three to four students.
- Think of how you can make a boat using some of the materials that you have.
- Draw a picture.
- Prepare a boat.
- Try to ensure that your boat is different from boats made by other groups.
- Organise an exhibition of boats in the class.
Question 2.
Compare your boat with other’s boats.
Answer:
| Strengths of your boat | Challenges of your boat |
| Floats well and holds weight. | May tilt if overloaded. |
| Made from light and waterproof materials. | Cardboard may get soggy if not waterproofed. |
| Good balance and stability. | Needs strong joints to avoid breaking apart. |
Let Us Reflect Page 115-116
Question 1.
Enquire about something
When Ravi spins a spinner, he notices that it slows down and eventually stops. He is curious about this and asks his teacher some questions. List at least two questions that he could ask
Answer:
When Ravi spins the spinner, he notices that it slows down and stops. He could ask:
- Question 1 ‘Why does the spinner stop spinning on its own?’
- Question 2 ‘Is something making the spinner slow down?’
Question 2.
Figure it out
(a) The following figure is bending towards the side ‘A’. What should be done to balance it?
(b) How would you make a floating object sink and a sinking object float?
Answer:
(a) We can add some weight to side ‘B’ or remove some weight from side ‘A’ to make it straight and balanced.
(b) To make a floating object sink Put something heavy on it.
To make a sinking object float Tie something light like a balloon or foam to it.
Question 3.
Do an activity
Classify the objects below based on whether they float or sink in water.
Answer:
| Things that float | Things that sink |
| Wax | Marble |
| Cork | Spoon |
| Leaf | Coin |
| Thermocol | Eraser |
| Candle | Lemon |
| Ice-cube | Potato |
| Pumpkin | Tomato |