Answers:
Situation 1:
1 Hang a pen by a piece of string. Question:
a Is the pen at rest or in motion?
The pen is at rest.
b. Are there forces acting on the pen?
Yes, it's own weight and the tension force of the string that holds it.
2. Cut the string with a pair of scissors Question:
What happens to the pen?
It falls down.
What could have caused the pen's motion?
The elimination of the tension force of the string leaves us only with the weight of the pen. As the weight is a force that pulls objtect down, the pen falls down.
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Situation 2:
1. Place a book on top of a table. Question:
a. is the book at rest or in motion?
The book is at rest.
b. Are there forces acting on the book?
Yes, it's own weight and the normal force that the table makes with an opposite direction and same magnitude as the weight.
2. Push the book in one direction and push it in the opposite direction at the same time with the same amount of forces,
Question: Did the book move?
It did not move
How will you make the book move? Write your conclusion.
If we want to make the book move, we'll have to make that the forces acting on it are not equal in the same axis. For example, if we want to move it upwards, we'll have to apply a force that is greater than it's weight, which is force that pushes downwards.
