Test the hardness of the following objects by scratching two objects at a time. Refer to step 1 to easily identify which object is harder than the other.
(a) Object A - pencil
(b) Object B - sandpaper
(c) Object C - iron nail
(d) Object D - copper penny
(e) Object E - glass
(f) Object F - knife
Answer (2)
The hardness of various objects can be ranked based on the Mohs Hardness Scale, with sandpaper being the hardest and pencil the softest. Sandpaper can scratch glass, glass can scratch copper, and a knife can scratch all except for very hard materials like sandpaper itself. The experiment involves scratching these items to visually and physically determine their relative hardness.
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To test the hardness of different objects using the scratch test, you'll compare each pair of objects to determine which one is harder. In this method, the harder material will scratch the softer one. Here's how you can approach it step-by-step:
Object A - Pencil vs. Object B - Sandpaper :
Sandpaper is likely to scratch a pencil. Therefore, sandpaper is harder than the pencil.
Object B - Sandpaper vs. Object C - Iron Nail :
An iron nail is made of metal and will not be scratched by sandpaper. Therefore, the iron nail is harder than sandpaper.
Object C - Iron Nail vs. Object D - Copper Penny :
An iron nail will scratch a copper penny because iron is generally harder than copper. Therefore, the iron nail is harder.
Object D - Copper Penny vs. Object E - Glass :
Glass will scratch a copper penny, indicating that glass is harder than copper.
Object E - Glass vs. Object F - Knife :
It depends on the material of the knife. If it's a standard steel knife, it will usually be able to scratch glass, indicating it is harder.
To conclude, based on this scratch test, the order from hardest to softest is likely:
Knife
Glass
Iron Nail
Copper Penny
Sandpaper
Pencil
This series of scratch tests helps illustrate how we can use material properties, such as hardness, to differentiate between substances. This approach is fundamental in the field of materials science and useful in various practical applications, such as selecting materials for construction or crafting.
