Hang a pen by a piece of string.
1.Is the pen at rest or in motion, explain.
2.are there forces acting of the pen?explain.

cut the string with a pair of scissors
3.what happens to the pen?what could have caused the pen's motion?explain.

place a book on the top of a table
4.is the book at rest, or in motion?explain.
5.are there forces acting on the book?explain.

1. No, the pen is at rest, it doesn't move.
2. Yes, tension force applied by the string and gravitational force of the earth.
3. The pen definitely falls down, because the gravitational force is acting on it.
4. The book is at rest, it doesn't move.
5. Yes, normal force is applied by the table and the gravitational force of the earth.

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