Students can use Our Wondrous World Class 4 Solutions Chapter 7 How Things Work Class 4 Questions and Answers as a quick reference guide.
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
Discuss (Page 108)
Question 1.
Which of the spinners did not spin properly? Discuss the possible reasons.
Answer:
The spinners which did not spin properly are:
1. Toothpick away from the centre
Reason: The spinner was unbalanced because the toothpick was not in the middle. It wobbled and quickly stopped.
2. Square spinner
Reason: A square shape is not even on all sides, so it doesn’t spin smoothly. It shakes and falls quickly.
3. Other spinner (like a bottle cap)
Reason: It may not have been balanced or light enough. If it’s too heavy or uneven, it won’t spin well.
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, I noticed the position of the hole in the first two spinners.
- In the first spinner, the toothpick was at the centre, and it spun well.
- In the second spinner, the toothpick was away from the centre, and it did not spin properly.
This shows that the position of the hole makes a big difference. When the hole is in the centre, the spinner stays balanced and spins smoothly. If the hole is off-centre, the spinner wobbles and quickly falls.
Question 3.
What happens to the colours on the spinner when it is painted with different colours and then spun? (Page 109)
Answer:
When the spinner is painted with different colours and then spun, the colours appear to blend together and may look like a single new colour or become blurry due to the rapid action.
Question 4.
Many things around us spin, such as ceiling fans and potter’s wheels. What other things have you observed spinning? (Page 109)
Answer:
I have observed many things that spin around me, like:
- A top
- Washing machine drum
- Car tires
- Toy fidget spinner
- Bicycle wheels
- Spinning top
- Blender blades
- Merry-go-round in the park
Discuss (Page 111)
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, all light objects did not float but all the heavy objects sank. No, heavy object floated. The lighter objects that sank was iron nail or pin.
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. Some objects are too heavy, uneven, or shaped in a way that makes spinning hard for them. But many objects can spin. Here are a few objects that can spin:
- A spinning top
- A.bicycle wheel
- A fidget spinner
- Striker
- A ceiling fan
- A coin
- A merry-go-round
- Ball
Question 2.
Collect the objects mentioned in the table given below. Spin and observe them. Then, complete the table.
Answer:
Activity 2 (Pages 106-107)
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:
Activity 3 (Page 110)
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:
Activity 4 (Page 112)
Let us find out whether shape plays a role in floating and sinking.
Answer:
Activity 5 (Pages 113-114)
Question 1.
Let us create some boats:
- 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.
Following are some different types of boats which can be made.
Answer:
Students to do this activity themselves as directed.
Question 2.
Compare your boat with others’ boats.
Answer:
| Strengths of your boat | Challenges of your boat |
| I made a boat using cardboard. It was sturdy and floated well. | It could not last long as the card board turned into pulp after sometime. |
| I made a boat using aluminium foil. Being light it floated well. | Though the boat floated well but it overturned when I switched on the ceiling fan as it was made of light material. |
This is a suggestive answer. Students may write their own experiences.
Let us Reflect (Pages 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:
Two questions that Ravi could ask his teacher about why the spinner slows down and stops:
- Why does the spinner go slower and slower after I spin it?
- What makes the spinner stop spinning?
Question 2.
Figure it out
(a) The following figure is bending towards the side ‘A’. What should be done to balance it?
Answer:
The figure is bending towards side ‘A’. To balance it, we should try one of the following methods.
- Add weight to side ‘B’: You could attach another origami figure or a small object to the string hanging from side ‘ B ‘.
- Move the hanging point closer to side ‘A’: If the string from which the entire object is hanging is moved slightly towards side ‘A’, it might shift the balance.
- Reduce weight on side ‘A’: If possible, you could try using a lighter origami figure or removing the figure hanging on side ‘A’.
(b) How would you make a floating object sink and a sinking object float?
Answer:
To make a floating object sink, you can add weight to it and making it heavy or you can change its shape by crumpling it into a tight ball.
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 | Coin |
| Leaf | Spoon |
| Thermocol | Potato |
| Candle | Tomato |
| Lemon | Pumpkin |
| Ice-cube | Eraser |