Charge Clash Review Worksheet Charge Clash
Coulomb's Law Review Challenge (Simplified)
Name:
Date:
Quick Memory Trick
• Opposites Attract: Positive (+) and Negative (-) pull together.Sames Repel: Same charges push apart.Distance Rules: Moving closer makes the push or pull much stronger !
1
Part 1: Electrostatic Basics
1. Two positive (+) balloons push apart (repel) each other. If you swap one balloon to a negative (-) balloon, what happens to the electric force?
A They now attract (pull together) with the exact same strength.
B They push apart even harder than before.
C The force between them disappears completely.
D They still repel each other with the same strength.
2. Why does bringing two charged spheres 10 times closer make the force so much stronger than making one charge 10 times bigger?
A Distance (r) is on top of the formula, so it has more power.
B Distance is squared (r × r) at the bottom, so distance changes have a double-impact on force!
C The constant k changes size when objects are moved around.
D Distance does not affect the size of the electrostatic force.
2
Part 2: Visual Force Predictions
Predict what happens to the starting force (F ) when you change charges or distance. Use the clues!
Initial Setup The Change We Make Logic Helper Clue New Force (terms of F) Charges q1, q2, Dist. r Double charge q1 only 2 × charge = 2 × force 2F (Example) Charges q1, q2, Dist. r Double both charges (q1 and q2) 2 × 2 = 4 times the charge product Charges q1, q2, Dist. r Double the distance (2r) Further apart = weaker! Divide force by (2 × 2)
|
| Charges q1, q2, Dist. r | Cut distance in half (½r) | Closer together = stronger! Multiply force by (2 × 2) |
|
| Charges q1, q2, Dist. r | Double q1 AND Double distance r | Multiply by 2 for charge, divide by 4 for distance |
|
Page 1 • Turn over for Word Problems
Part 3: Showdown Scenarios
constant
k = 9.0 × 109
Scenario C: The Friction Comb
Standard Practice
A plastic comb gets statically charged, reaching a negative charge of -3.0 × 10-6 C. It is held 0.3 meters away from a paper bit with a positive charge of +1.5 × 10-6 C. Find the electric force between them.
1. Identify Variables
q1 (Comb Charge): 3.0 × 10-6
q2 (Paper Charge): 1.5 × 10-6
r (Distance): 0.3 m
r2 (0.3 × 0.3):
2. Math Scratchpad
Attractive (Opposites Pull)
Repulsive (Sames Push)
Force (N):
Scenario D: The Dust Particle Drift
Convert cm → m
A tiny dust particle has a charge of 2.0 × 10-9 C. It drifts close to a metal plate with a charge of -4.0 × 10-9 C. The distance is 5.0 cm. Find the electrostatic force.
⚠️ ALERT: Divide 5.0 cm by 100 to get meters first!
5.0 cm ÷ 100 = 0.05 m
1. Identify Variables
q1 (Dust Charge): 2.0 × 10-9
q2 (Plate Charge): 4.0 × 10-9
r (Distance in m): 0.05 m
r2 (0.05 × 0.05):
2. Math Scratchpad
Attractive (Opposites Pull)
Repulsive (Sames Push)
Force (N):
Page 2 • End of Coulomb's Law Review
Force Finder Worksheet Force Finder
Coulomb's Law Practice & Differentiated Tracks
Name:
Date:
L1
Concept Track: Word banks and conceptual sentence guides.
L2
Core Track: Standard numerical solving with variable checklist.
L3
Spicy Track: Advanced proportional reasoning and algebraic extensions.
The Force Toolbox
F =
k • q1 • q2 r2
k (Constant): 9.0 × 109 N•m2/C2
q (Charge): Coulombs (C) • r (Distance): Meters (m)
Centimeters (cm) → Divide by 100 first!
L1
Part 1: Concept Builder (Logic Stems)
Word Bank for Support:
increase (gets stronger) decrease (gets weaker) numerator (directly proportional) denominator (inversely proportional)
1. If you push two charged balloons closer together (decreasing distance r)...
The electrostatic force will because distance is in the .
2. If you add more static charge to a plastic rod (increasing charge q)...
The electrostatic force will because force is directly proportional to .
Page 1 • Turn over for Math Tracks
Part 2: Practice Tracks
[ ] Meter-Check [ ] r-squared [ ] Math Done
L2 Scenario A: Balloon Attraction
Basic Math
A balloon with a charge of 1.0 × 10-6 C is 0.5 m away from another balloon with a charge of 2.0 × 10-6 C.
1. Identify Variables
q1 = __________________
q2 = __________________
r = __________________
2. Show Your Math
Answer (N):
L2 Scenario B: The Static Spark
Conversion Check
Finger charge: 3.0 × 10-9 C. Knob charge: -3.0 × 10-9 C. Distance: 2.0 cm.
STOP! Convert 2.0 cm to METERS first! (2.0 cm ÷ 100 = 0.02 m)
1. Identify Variables
q1 = 3.0 × 10-9 C
q2 = 3.0 × 10-9 C
r = __________________ m
2. Show Your Math
Answer (N):
L3 Scenario C: Proportional Logic Challenge
Spicy Track
Two point charges experience a starting electrostatic force of F = 1.2 × 10-3 N. If you double the charge of q1 AND double the distance r, what is the new electrostatic force?
1. Explain the Logic
Static Secrets Teacher Guide Static Secrets
Teacher Facilitation & Answer Key
Lesson Context
This lesson prioritizes visual scaffolding for Coulomb's Law. Many students struggle with the inverse square relationship (distance) and algebraic manipulation. Use the provided "Solution Checklist" and structured grids to guide their independent work.
Learning Objectives
Explain the inverse relationship between distance and force.
Convert cm to m correctly within a physics context.
Apply a 5-step checklist to solve numerical static force problems.
Watch For These!
The "r × 2" Mistake:
Students often double the distance instead of squaring it. Use Slide 3 to visually show why distance matters so much more than charge.
Invisible Exponents:
Remind students that a calculator requires (EE) or (exp) buttons. Multiplying by 10 and then using the carrot (^) leads to errors.
Differentiation Strategies
1. Formula Mastery
The Formula Triangle is critical. If a student is looking for F , they cover F and see they must multiply top variables and divide by r2. This bypasses the need for complex algebraic isolation.
2. Language Scaffolds
The Part 1 sentence stems reveal logic before math . If a student can't explain why force increases when distance decreases, the math will likely be wrong anyway.
F k•q1•q2 r²
Reference Guide
Full Answer Keys
Force Finder Worksheet Answer Key
Part 1: Conceptual Logic Stems
Q1 (Balloons closer): "...will increase because distance is in the denominator, so dividing by a smaller number makes the force larger."Q2 (More charge): "...will increase because force is directly proportional to charge (top variables)."
Part 2: Math Results
Scenario A (Balloon Attraction - L1/L2): 0.072 Nq1 = 1.0 × 10-6 C, q2 = 2.0 × 10-6 C, r = 0.5 m → F = 9e9 × 2e-12 / 0.25 = 0.072 N
Scenario B (The Static Spark - L2): 2.025 × 10-4 NConvert 2.0 cm → 0.02 m. r2 = 0.0004. F = 9e9 × 9e-18 / 0.0004 = 2.025 × 10-4 N
Scenario C (Proportional Challenge - L3): 6.0 × 10-4 NDoubling charge doubles force (2F). Doubling distance divides force by 4 (F/4). Total scaling is 2/4 = ½. New force = 1.2 × 10-3 N × ½ = 6.0 × 10-4 N.
Charge Chaos Slides Charge Chaos
Mastering Coulomb's Law Step-by-Step
The Static Spark
Bad Hair Day
Ever wonder why your hair stands up when you take off a sweater? That's Electrostatic Force in action!
Nature's Battery
Lightning is just a massive discharge of force between charged clouds and the ground.
"Why do objects pull or push each other without touching?"
The Distance Rule
Close Together
Small distance (r)
HUGE FORCE
Far Apart
Large distance (r)
WEAK FORCE
The Visual Formula
F k•q1•q2 r²
F = Force (Newtons)
q = Charge (Coulombs)
r = Distance (Meters)
The Solution Checklist
1
Identify
Circle charges & distance.
2
Convert
Units must be in meters .
3
Square
Calculate (r × r).
4
Multiply
k • q1 • q2
5
Divide
Divide top by r2
Practice Together
Two balloons: 1.0 × 10-6 C and 2.0 × 10-6 C. Distance: 0.5 m.
k = 9.0 × 109
r2 = 0.5 × 0.5 = 0.25
The Setup
(9×109) • (1×10-6) • (2×10-6)
0.25
FORCE = 0.072 N
Think Like a Scientist
"If I double the distance between two balloons, the electric force will because..."
"When the charge on a rod increases, the force it exerts because..."
Class Vote: Concept Clash
Two positive (+) balloons push apart (repel) each other. If you swap one balloon to a negative (-) balloon, what happens to the force?
A
They now attract (pull together) with the exact same strength.
B
They push apart even harder than before.
C
The force between them disappears completely .
D
They still
