What are 20 physical changes ?

Crushing a can.

Melting an ice cube.

Boiling water.

Mixing sand and water.

Breaking a glass.

Dissolving sugar and water.

Shredding paper.

Chopping wood.

Explanation:

Crushing a can

Melting an ice cube

Boiling water

Mixing sand and water

Breaking a glass

Dissolving sugar and water

Shredding paper

Chopping wood

Mixing red and green marbles

Sublimation of dry ice

Crumpling a paper bag

Melting solid sulfur into liquid sulfur. This is an interesting example since the state change does cause a color change, even though the chemical composition is the same before and after the change. Several nonmetals, such as oxygen and radon, change color as they change phase.

Chopping an apple

Mixing salt and sand

Filling a candy bowl with different candies

Vaporizing liquid nitrogen

Mixing flour, salt, and sugar

Mixing water and oil

Explanation:

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).