Question

Classify the following into slow and fast changes:
i. Spinning of top
ii. Formation of day and night
ii. Formation of curd from milk
iv. Change of season
v. Making curd from milk by adding lemon juice.

Answer 1

The change of matter is mainly classified into two main categories that is a physical change and chemical change. Depending on the time required to change the matter again we can classify the changes into fast changes and slow changes.

Complete answer:
As we know that matter can change from one form to another form. Based on the type of changes we can classify the changes into the following two main categories.
1. Physical Change: In this type of change matter does not change its identity. Only there is a change in physical properties of matter like size, shape, state and color of matter.
2. Chemical Change: In this type of change matter converted into a new substance with different properties.

Apart from these two main categories, we can also classify the changes which we observe in our everyday life depending on the rate of change of matter as follows:
1. Fast change: In this type of change matter takes less than an hour to change.
2. Slow Change: In this type of change matter takes a day to change.

Now, using the rate of change of matter we can classify the given changes into slow and fast change.
i. Spinning of top: It is a fast change as it takes a few minutes.
ii. Formation of day and night: Rotation of earth around its own axis causes the formation of iii. day and night. It is a slow change as the earth takes 24 hours to complete one rotation around its own axis.
iv. Formation of curd from milk: It is a slow change as it takes 5-6 hours to change milk into curd.
v. Change of season: It is a slow change as it takes a few months to change the season.
Making curd from milk by adding lemon juice: It is fast changing as adding lemon juice increases the rate of curdling the milk.

Note:
So by measuring the time required to change the matter we can classify the changes into slow and fast changes. In our everyday life, we observed many slow and fast changes. Slow change takes place in a long period while fast changes take place in a short period of time.