Name: Leevian Chen Date: November 6th, 2020
Student Exploration: Pith Ball Lab
Directions: Follow the instructions to go through the simulation. Respond to the questions and
prompts in the orange boxes.
Vocabulary: Coulomb’s law, electrostatic force, gravitational force, induced charge, pith ball, Pythagorean
Theorem, tension, vector
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. A girl rubs a balloon on her head and then holds it a short distance away.
Why does her hair stick to the balloon?
The electrons of her hair move to the balloon, allowing the balloon
to be negatively charged and her hair positively charged. Since
her hair is positively charged it becomes attracted to the balloon
which is negatively charged.
2. Why do you think the individual strands of hair are spread apart?
Since the hair is positively charged they repel each other.
Gizmo Warm-up
The girl’s hair was attracted to the balloon by the electrostatic force, a force
between all charged objects. Most objects acquire a charge (q) by gaining or
losing electrons. Objects that gain electrons become negatively charged, while
objects that lose electrons become positively charged.
The Pith Ball Lab Gizmo shows two pith balls hanging by strings. Pith balls are
made from lightweight material that can easily acquire a charge. To begin, check
that the charge on each pith ball (q1 and q2) is 0.0 × 10-6 coulombs (C).
Use the sliders to test each combination of charges listed below. State whether the electrostatic force is
attractive (balls move together), repulsive (balls move apart), or zero (balls don’t move).
Charge on left ball (q1 ) Charge on right ball (q2 ) Electrostatic force
Positive Zero Zero
Zero Negative Zero
Positive Positive Repulsive
Negative Negative Repulsive
Positive Negative Attractive
Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
, Get the Gizmo ready:
Activity A:
2 to 0.0 × 10-6 C.
● Set q1 and q
Coulomb’s law ● Set the mass of the pith balls to 5 grams.
● Check that g is 9.8 m/s2 and L is 0.50 m.
Question: What factors affect the force between charged objects?
1. Summarize: Summarize what you have learned so far by filling in the blanks:
If the two charges are the same, the force is Repulsive
If the two charges are opposite, the force is Attractive
If one of the charges is zero, the force is Zero
izmo does not show induced charge. An induced charge occurs
*Note: For simplicity, the Pith Ball Lab G
when a charged object is brought near a neutral object, causing the electrons in the neutral object to move
away from or towards the charged object. This results in an attractive force between the charged object
and the neutral object.
2. Predict: How do you think the strength of electrostatic force is related to the charges on the balls and the
distance between them?
A higher charge will produce a higher force because it is directly proportional.
3. Observe: Set q1 to -5.0 × 10-6 C. Gradually decrease q2 below 0.0 × 10-6 C.
A. What do you observe? As q2 decreases, the pith balls repel each other further
and further apart.
B. What does this tell you about the force When q2 decreases the repulsive forces between the
between the pith balls? two pith balls increase.
4. Observe: Now slowly increase q2 above 0.0 × 10-6 C. What do you observe, and what does this tell you
about the electrostatic force?
As q2 increases, the balls move closer and closer together. When above 0.3 × 10-6 C,
the pith balls are pulled closely together. This means that the electrostatic force is an
attractive force and increases as q2 increases.
Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
Student Exploration: Pith Ball Lab
Directions: Follow the instructions to go through the simulation. Respond to the questions and
prompts in the orange boxes.
Vocabulary: Coulomb’s law, electrostatic force, gravitational force, induced charge, pith ball, Pythagorean
Theorem, tension, vector
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. A girl rubs a balloon on her head and then holds it a short distance away.
Why does her hair stick to the balloon?
The electrons of her hair move to the balloon, allowing the balloon
to be negatively charged and her hair positively charged. Since
her hair is positively charged it becomes attracted to the balloon
which is negatively charged.
2. Why do you think the individual strands of hair are spread apart?
Since the hair is positively charged they repel each other.
Gizmo Warm-up
The girl’s hair was attracted to the balloon by the electrostatic force, a force
between all charged objects. Most objects acquire a charge (q) by gaining or
losing electrons. Objects that gain electrons become negatively charged, while
objects that lose electrons become positively charged.
The Pith Ball Lab Gizmo shows two pith balls hanging by strings. Pith balls are
made from lightweight material that can easily acquire a charge. To begin, check
that the charge on each pith ball (q1 and q2) is 0.0 × 10-6 coulombs (C).
Use the sliders to test each combination of charges listed below. State whether the electrostatic force is
attractive (balls move together), repulsive (balls move apart), or zero (balls don’t move).
Charge on left ball (q1 ) Charge on right ball (q2 ) Electrostatic force
Positive Zero Zero
Zero Negative Zero
Positive Positive Repulsive
Negative Negative Repulsive
Positive Negative Attractive
Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
, Get the Gizmo ready:
Activity A:
2 to 0.0 × 10-6 C.
● Set q1 and q
Coulomb’s law ● Set the mass of the pith balls to 5 grams.
● Check that g is 9.8 m/s2 and L is 0.50 m.
Question: What factors affect the force between charged objects?
1. Summarize: Summarize what you have learned so far by filling in the blanks:
If the two charges are the same, the force is Repulsive
If the two charges are opposite, the force is Attractive
If one of the charges is zero, the force is Zero
izmo does not show induced charge. An induced charge occurs
*Note: For simplicity, the Pith Ball Lab G
when a charged object is brought near a neutral object, causing the electrons in the neutral object to move
away from or towards the charged object. This results in an attractive force between the charged object
and the neutral object.
2. Predict: How do you think the strength of electrostatic force is related to the charges on the balls and the
distance between them?
A higher charge will produce a higher force because it is directly proportional.
3. Observe: Set q1 to -5.0 × 10-6 C. Gradually decrease q2 below 0.0 × 10-6 C.
A. What do you observe? As q2 decreases, the pith balls repel each other further
and further apart.
B. What does this tell you about the force When q2 decreases the repulsive forces between the
between the pith balls? two pith balls increase.
4. Observe: Now slowly increase q2 above 0.0 × 10-6 C. What do you observe, and what does this tell you
about the electrostatic force?
As q2 increases, the balls move closer and closer together. When above 0.3 × 10-6 C,
the pith balls are pulled closely together. This means that the electrostatic force is an
attractive force and increases as q2 increases.
Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved
