Question

1.why does it happen


1.fruits can be easily but with a sharp knige

Answer 1

For organic matter, such as fruit, cutting is a straightforward process because cells/tissues/proteins/etc can be broken apart with relatively little energy. This is because organic matter is much more flexible and the molecules bind through weak intermolecular interactions such as hydrogen bonding and van der Waals forces. A normal knife simply puts so much pressure on the material locally, that it breaks or tears. Having said that, the physical explanation for what happens in detail when materials break is complicated and not fully understood, yet, so your question is perfectly valid. Actually, if you wanted to, you could make a career out of it as a solid state physicist or material scientist, because there is great importance in having materials that are harder to break or tear!

Answer 2

We know that pressure depends upon area. As there is less area in sharp knife then then pressure increases . So, it is easy to cut the fruits by sharp knife.