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Questions and Answers
What is usually greater when something moves on a rough surface compared to a smooth surface?
What is usually greater when something moves on a rough surface compared to a smooth surface?
Why does car A go further and faster than car B?
Why does car A go further and faster than car B?
What is one of the benefits of friction?
What is one of the benefits of friction?
What problem is caused by friction in machines?
What problem is caused by friction in machines?
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What is a way to reduce the unwanted effects of friction?
What is a way to reduce the unwanted effects of friction?
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What is the minimum force needed to make the block start moving?
What is the minimum force needed to make the block start moving?
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What is the effect of friction on the eraser?
What is the effect of friction on the eraser?
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Why does the train go slow down?
Why does the train go slow down?
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What is one of the problems caused by friction?
What is one of the problems caused by friction?
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What is one of the benefits of friction in daily life?
What is one of the benefits of friction in daily life?
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Study Notes
Light and Shadow
- A shadow is formed when the path of light is blocked by an object.
- Transparent materials, like clear glass, do not form shadows when light sources are blocked, while opaque materials, like boxes, do form shadows.
- The size, length, and position of a shadow can change depending on the position of the object and light source.
- Moving the object closer to or further from the light source affects the size of the shadow.
- Materials can be classified as transparent, translucent, or opaque based on how they interact with light.
The Earth and The Moon
- The Earth is a spherical object with a rocky crust.
- The Moon is a natural satellite of the Earth, taking 29 days to orbit it.
- The Moon has craters formed by space rocks hitting its surface.
- The Sun is a star at the center of our Solar System, providing light to the Earth and Moon.
- Every object with mass has gravity, pulling everything towards its center.
- Moon phases change as the Moon orbits the Earth, with different amounts of the light and dark sides visible from Earth.
- The Moon's phases appear differently from the northern and southern hemispheres.
Mixture and Filtration
- Matter has mass and can be in solid, liquid, or gas states.
- Solids have a fixed shape and volume, while liquids take the shape of their container and have a fixed volume.
- Gases have no fixed shape or volume and can flow freely.
- A mixture is when two or more substances are physically combined but not chemically combined, and can be separated again.
- Examples of mixtures include sand and iron, flour and paper, and rice and steel nails.
- Soluble substances dissolve in a liquid, while insoluble substances do not.
- Filtration is a process that makes a substance more pure or clean.
Force and Magnet
- Force is a push or pull that creates motion, makes things change direction or shape, and can be measured in newtons (N).
- Forces can be used to make things move, stop, or change direction.
- Friction is a force that opposes motion when two surfaces are in contact, making things slow down and stop.
- The type of surface affects the amount of friction, with rough surfaces having more friction than smooth surfaces.
- Friction has benefits, such as enabling us to hold on to things and walk without slipping, but also causes problems like wear and tear.
- We can reduce the unwanted effects of friction by applying oil to moving parts or using smooth surfaces.
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Description
Assessment quiz on the concept of light and shadow for Grade 3 students, covering the formation of shadows and the path of light.