How Things Work

Given: We need to think about whether all objects can spin and list some that can.

Concept: Spinning means rotating around a central point or axis. Objects that are round, balanced, or have a pointed base tend to spin well.

Answer: No, not all objects can spin easily. Objects that are round, symmetrical, or have a smooth surface spin better.

Objects that can spin:
1. Top (spinning top / lattu)
2. Coin
3. Ball
4. Wheel
5. Bangle
6. CD or disc
7. Globe
8. Fan blades

Final Answer: Not all objects can spin. Rounded, symmetrical objects like coins, tops, bangles, and balls spin well.

Given: We spin different objects and record observations, questions, and thoughts.

Concept: When objects spin, they behave differently based on their shape, weight, and balance. Symmetrical and round objects spin longer and more smoothly.

Completed Table:

Coin:
- I observe: As it slows down, it begins to shake and wobble before falling flat.
- I wonder: Why does it start to shake as it slows down?
- I think: As it loses speed, it cannot balance itself upright anymore, so it wobbles and falls.

Bangle:
- I observe: As time passes, the sound becomes louder and faster just before it stops.
- I wonder: Why does the sound change as it slows down?
- I think: As the bangle tilts more and hits the surface more frequently, the sound increases before it stops.

Pencil:
- I observe: The pencil does not spin smoothly; it wobbles and falls quickly.
- I wonder: Why does the pencil not spin as long as a top?
- I think: Because the pencil is not perfectly round or balanced, it cannot spin steadily.

Piece of Stone:
- I observe: The stone barely spins; it just rolls or tips over immediately.
- I wonder: Why can't a stone spin like a top?
- I think: Because a stone has an irregular shape and is not balanced, it cannot spin properly.

Wooden Spinner (Top):
- I observe: The top spins smoothly for a long time and stays upright while spinning fast.
- I wonder: Why does the top stay upright while spinning?
- I think: Because the top is designed with a pointed base and balanced shape, it spins steadily for a long time.

Eraser:
- I observe: The eraser spins for a short time and quickly falls to one side.
- I wonder: Why does the eraser not spin as well as a coin?
- I think: Because the eraser is rectangular and not symmetrical, it loses balance quickly.

Final Answer: Round and symmetrical objects (like coins and tops) spin better and longer. Irregular-shaped objects (like stones and erasers) do not spin well.

Given: We observe how different changes to a spinner affect its spinning.

Concept: A spinner works best when it is balanced and the pivot (toothpick) is exactly at the centre. Shape and balance affect how well and how long a spinner spins.

Completed Table:

Toothpick at the centre:
- What do you observe? Spins
- Any other observations: Spins smoothly and for a longer time because it is balanced.

Toothpick away from the centre:
- What do you observe? Spins, but not well
- Any other observations: Wobbles and falls quickly because it is unbalanced.

A square spinner:
- What do you observe? Spins, but not smoothly
- Any other observations: The corners make it wobble; it does not spin as long as a circular spinner.

Circular spinner with a circular mark on its body:
- What do you observe? Spins
- Any other observations: The circular mark appears to blur or form a pattern when spinning fast; the mark seems to move in a circle.

Any other (e.g., triangular spinner):
- What do you observe? Spins briefly
- Any other observations: Irregular shapes do not spin as smoothly or as long as circular ones.

Final Answer: A circular spinner with the toothpick exactly at the centre spins the best. Balance and shape are key factors for good spinning.

Given: We drop various objects in water and observe whether they float or sink.

Concept: Whether an object floats or sinks depends not only on its weight but also on its shape and the amount of water it displaces. An object floats if it displaces water equal to its own weight.

Completed Table:

Leaf:
- Guess: F (Float) | Reason: It is light
- Observation: F (Float) | Reason: It is light and its flat shape helps it stay on the surface.

Iron nail or pin:
- Guess: S (Sink) | Reason: It is heavy and made of metal
- Observation: S (Sink) | Reason: Iron is denser than water; it sinks despite being small.

Empty steel bowl:
- Guess: S (Sink) | Reason: It is made of metal
- Observation: F (Float) | Reason: The bowl shape traps air inside, making it less dense overall, so it floats.

A piece of stone:
- Guess: S (Sink) | Reason: It is heavy
- Observation: S (Sink) | Reason: Stone is denser than water.

Empty bottle with a closed lid:
- Guess: F (Float) | Reason: It is light and has air inside
- Observation: F (Float) | Reason: The air trapped inside makes it less dense than water.

Bottle full of water with a closed lid:
- Guess: S (Sink) | Reason: It is heavy with water inside
- Observation: S (Sink) | Reason: It is now denser than the surrounding water.

Final Answer: Floating or sinking depends on both the weight and the shape of the object. An empty bowl floats even though it is made of metal, because its shape traps air.

Given: We need to discuss whether weight alone decides if an object floats or sinks.

Concept: Floating and sinking depend on density and shape, not just weight. An object floats if it is less dense than water or if its shape allows it to displace enough water.

Answer:
No, not all light objects float and not all heavy objects sink.

Heavy objects that floated:
- Empty steel bowl — it is made of heavy metal, but its cup shape traps air, so it floats.
- A large ship — made of heavy steel, but floats because of its hollow shape.

Lighter objects that sank:
- A small iron pin or nail — though very light in weight, it is dense and sinks.
- A small pebble — lighter than a bowl but still sinks because it is denser than water.

Conclusion: Floating or sinking of an object cannot be decided based just on whether it is heavy or light. It also depends on the shape of the object and how much water it displaces.

Final Answer: Shape and density are equally important. A heavy steel bowl floats because of its shape, while a tiny iron pin sinks because of its high density.

Given: We test aluminium foil in three different shapes to see if shape affects floating or sinking.

Concept: Shape affects how much water an object displaces. A flat or cup-shaped object displaces more water and can float, while a compact ball shape displaces less water and sinks.

Completed Table:

Spread out:
- Guess: F (Float) | Reason: It is thin and light; the flat shape will rest on water.
- Observation: F (Float) | Reason: The flat shape spreads the weight over a large area and displaces enough water to float.

Pressed tightly into a ball:
- Guess: S (Sink) | Reason: It becomes compact and heavy for its size.
- Observation: S (Sink) | Reason: The ball shape displaces very little water; it is denser than water in that form, so it sinks.

In a cup-like shape:
- Guess: F (Float) | Reason: Like a bowl, it will trap air and float.
- Observation: F (Float) | Reason: The cup shape traps air inside, making it less dense overall, so it floats.

Conclusion: By changing the shape of the same piece of aluminium foil, we can make it float or sink. Shape plays an important role in floating and sinking.

Final Answer: The same aluminium foil floats when spread out or cup-shaped, but sinks when pressed into a tight ball. This proves that shape determines whether an object floats or sinks.