Changes in objects can usually be observed. The properties of objects can be compared between before and after the change . Something has changed color. Some have changed their shape, some have become soft. There are several factors that money can cause changes in objects, (Haryanto, 2006: 81-86), namely:
1) Warming up
Watch the water being heated! The still water in the pot will become a turbulent liquid. Eventually steam will come out of the pot. Ice cubes left in the open air will eventually melt. The room temperature which is higher than the air temperature in the freezer causes the ice cubes to absorb heat and melt.
Heated butter will also melt or melt. However, if the butter is cooled, the butter solidifies again. So heating causes things to undergo physical changes. Solid form can change to liquid. Liquid form can turn into gas.
2) Cooling
Cooled water can turn into ice. Cooling water vapor can turn into water droplets again. For example, drink vapor that sticks to the glass lid will turn into water droplets again. So cooling causes objects to change state. The liquid state turns into a solid. The gaseous state changes to liquid.
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3) Combustion
Burnt paper will turn to ashes. The form of paper in the form of sheets turns into ash in the form of powder. The white color of the paper changes to black gray. Harder paper turns to brittle ash. The smell of paper and the smell of ash are also different. Likewise with wood burning. Wood will also experience some changes in properties. So burning can cause objects to change shape, color, hardness, flexibility and smell.
4) Mixing with water
Cement mixed with water initially becomes a thick liquid. However, over time the cement will solidify. The form of cement in the form of powder turns into a solid. Soft cement becomes hard cement. Likewise, when sugar and salt are mixed with water, then stirred, they will dissolve. The form of sugar is no longer visible. When the water is evaporated, the sugar or salt turns back into a solid. So, objects mixed with water can change shape and hardness.
5) Decay
Fruit, vegetables, or food that is left in the open air, over time will undergo a process of decay. A fruit or vegetable that was initially hard will eventually become soft and juicy. The color of the fruit or vegetable turns brown. The smell that was originally fragrant turned into a foul and unpleasant smell.
At first, the meat of animals and fish was chewy, but gradually it became soft and watery. The color changes to brown or black. The smell has also turned into a rotten and unpleasant smell. Animal meat and fish, which were originally chewy, gradually turned soft and watery. The color changes to brown or black. The smell also turned into rotten and unpleasant. So, decay can cause objects to change shape, color, flexibility, hardness and smell.
6) Rusting
Metals, such as iron and cells, when exposed to water or moisture, will gradually undergo a rusting process. The color of iron or zinc turns brown. Iron or zinc which was originally hard and sturdy turns into brittle and easily broken. So, rusting can cause objects to change color and hardness.