Observations:
- When the two pieces of the straw do not touch each other, there is no apparent change or movement observed.
- When the free end of the suspended straw is rubbed with a piece of paper, the straw becomes negatively charged.

Explanation:
When the two pieces of the straw do not touch each other, they are electrically neutral. This means that they have an equal number of positive and negative charges, resulting in no net charge. Therefore, there is no attraction or repulsion between the straws, and no movement or change is observed.

When the free end of the suspended straw is rubbed with a piece of paper, some of the electrons from the paper are transferred to the straw. This transfer of electrons makes the straw negatively charged, as it now has an excess of negative charges.

Electrostatic Force:
The interaction between the rubbed straw (negatively charged) and the suspended straw (electrically neutral) is due to electrostatic forces. Electrostatic force is the force of attraction or repulsion between charged objects.

Attraction and Repulsion:
When the negatively charged straw is brought near the suspended straw, the two straws exhibit an attractive force. This is because opposite charges attract each other. The positive charges in the suspended straw are attracted to the negatively charged straw, causing the suspended straw to move towards it.

If the two straws touch each other, the excess electrons from the rubbed straw will be transferred to the suspended straw. This transfer of charges neutralizes the rubbed straw, and both straws become electrically neutral. As a result, there is no longer any attraction or repulsion between them.

Understanding:
From this activity, we can understand the following:
- Like charges repel each other, and opposite charges attract each other.
- When an object gains or loses electrons, it becomes charged.
- The transfer of electrons can occur through rubbing or friction.
- The presence of electric charges can create attractive or repulsive forces between objects.

This activity helps in understanding the basic principles of electrostatics, which is the study of static electricity and the behavior of charged objects.