Wearing down of pencil lead is a physical change because the substance is still the same (graphite), just in a different form (smaller pieces). No new substances are formed during the process, making it reversible by simply sharpening the pencil to create a new point.
A worn down pencil is often referred to as a stub or nub.
Yes, crushing rocks is considered a physical change because the rocks are broken down into smaller pieces without changing their chemical composition. This process can be reversed by reassembling the pieces back together.
Writing with a pencil is an example of kinetic friction. This type of friction occurs between two surfaces in relative motion, such as the pencil tip and the paper, which creates heat and wears down the pencil lead over time.
your using the force called muscular force.
yoyo
Sharpening a pencil is a physical change, because there is no change to the chemical makeup of the pencil when sharpening it. It is simply chunks of wood being sliced off to reveal more of the lead.It is a physical change.
Water
Although they both still have the same basic elements (i.e. pencil and lead vs water), there is a physical state change that occurs when you freeze water to make ice. Sharpening/shaving down a pencil only results in a difference of shape and size. It's about the same as ripping paper vs burning paper. Also, freezing water to make ice is a reversible change (you can melt ice to turn it back into water) and shaving a pencil is an irreversible change (you can't sharpen a pencil and then put the pencil shavings back onto the pencil.)
Mountains are created by the physical process of pushing the Earth's crust up, while valleys and canyons are formed by the process of wearing down the crust through erosion.
physical weathering?
Since in breaking down there is no chemical change it's a physical change
i tink that it is a physical change
physical
physical
Physical or chemical
physical
The breaking down and wearing away of rocks is called weathering. This process can be caused by physical (mechanical) or chemical processes.