Part A: Effect of Spring Compression (Constant Added Mass = 50 g)
| Compression Setting | Trial 1 Distance (cm) | Trial 2 Distance (cm) | Trial 3 Distance (cm) | Average Distance (cm) |
|---|---|---|---|---|
| 1. Notch 1 (1 cm) | 44 | 46 | 45 | 45.0 cm |
| 2. Notch 2 (2 cm) | 178 | 182 | 180 | 180.0 cm |
| 3. Notch 3 (3 cm) | 402 | 408 | 405 | 405.0 cm |
Part B: Effect of Added Mass on Barrier Collision (Constant Compression = Notch 3)
| Added Mass (g) | Total Car Mass (g) | Trial 1 Blocks | Trial 2 Blocks | Avg Blocks Displaced |
|---|---|---|---|---|
| 0 g (Base Car) | 150 g | 2.0 | 2.0 | 2.0 blocks |
| 50 g | 200 g | 2.6 | 2.8 | 2.7 blocks |
| 100 g | 250 g | 3.2 | 3.4 | 3.3 blocks |
Create a scatter plot and draw a line of best fit representing the relationship between Added Mass (X-axis) and Average Blocks Displaced (Y-axis).
1
2
3
Blocks Displaced →
Added Mass (g) →
0
2.0
2.7
3.3
0g
50g
100g
Scale: 1 box = 1 block / 5g
Graph Checklist:
✓ Scaled Axes ✓ Unit Labels ✓ Plotted Points ✓ Best-fit Line
Calculated Slope:
Slope = 1.3 blocks / 100 g = 0.013 blocks/g added (proportional scaling)
Spring Racer Lab Report • Teacher Exemplar Page 2 of 3
TEACHER EXEMPLAR • CRITICAL ANALYSIS
CER ARGUMENT
1. Explain how compressing the spring launcher further (Notch 1 to Notch 3) affects elastic potential energy, speed, and distance. Is the relationship linear or quadratic?
The relationship between compression setting (which governs speed) and travel distance is strictly quadratic. Compressing the launcher from Notch 1 (1 cm) to Notch 2 (2 cm) doubled compression, but quadrupled the average travel distance (from 45 cm to 180 cm). Increasing to Notch 3 (3 cm) multiplied distance by 9 (405 cm). This perfectly supports the formula PE_elastic = 1/2 kx² and KE = 1/2 mv², demonstrating that kinetic energy increases quadratically with speed.
2. How did adding mass to the car (Part B) impact its final collision impact against the barriers? Analyze using Newton's Second Law and Kinetic Energy rules.
Adding mass increased collision impact linearly (0.013 blocks/g). Since release speed was constant, the initial kinetic energy was directly proportional to total mass (KE = 1/2 mv²). By Newton's Second Law, the heavier car (250g total) exerted a larger force on the barrier blocks during the sudden deceleration of impact, displacing 3.3 blocks compared to the base car's 2.0 blocks.
Claim
A model car's kinetic energy scales linearly with its total mass but quadratically with its launch speed, meaning speed increases have a vastly greater relative impact on collision forces than mass modifications.
Evidence
Doubling spring compression from 1 cm to 2 cm increased distance from 45.0 cm to 180.0 cm (a factor of 4.0). In Part B, launching the car at constant Notch 3 speed with mass scaling from 150g to 250g (a factor of 1.67) resulted in a direct linear rise in barrier block displacement from 2.0 blocks to 3.3 blocks (a factor of 1.65).
Reasoning
The potential energy stored in a spring is PE = 1/2 kx², which converts to Kinetic Energy (KE = 1/2 mv²). Since KE scales with the square of speed, doubling launch velocity (via spring compression) quadruples the car's initial kinetic energy. Consequently, the work friction must do to stop it (W = F_f • d) quadruples, leading to a quadratic distance scale. Conversely, KE scales linearly with mass (m). A car with 1.67 times the mass carries exactly 1.67 times the KE, meaning the impact force on the blocks during the collision is directly proportional to mass.
Teacher Sign-Off Checklist:
Launcher Safety Checked Data Validated Graph Formatted
Initials
T.R. (OK)
Spring Racer Lab Report • Teacher Exemplar Page 3 of 3
TOTAL GRADE / 16
Actionable Recommendations for Student Growth: Identify one "Glow" (success) and one "Grow" (target area) based on the criteria above.
Spring Racer Lab • Comprehensive Assessment Pack Page 1 of 2
SELF & PEER
Before submitting your finished report to your teacher, go through this list of scientific components with a partner to ensure no points are lost.
Setup & Data Integrity
Is my independent variable listed as added mass and spring compression setting?
Did I complete all three trials for each spring setting and mass and average them?
Are all distance measurements reported in centimeters (cm) and displacements in blocks?
Modeling & Argumentation
Did I use a consistent, linear scale on the grid so mass vs displacement points aren't squished?
Does my Claim directly and explicitly answer how mass and speed affect collision kinetic energy?
Does my Reasoning explain momentum, elastic potential energy, and kinetic energy scaling?
Exchange reports with a partner from a different lab group. Review their data collection and graphing sections and provide constructive, analytical feedback.
Author Name:
Reviewer Name:
Peer Glow (What was done exceptionally well) Highlight precise values, beautiful graphs, clear variable listings, or strong hypothesis structure.
Peer Grow (Actionable recommendation for improvement) Suggest specific ways to clarify calculations, adjust graph scales, or integrate physics laws into reasoning.
✓
Authenticity & Integrity Pledge I verify that all recorded data represents our group's actual empirical measurements.
Author Signature
Spring Racer Lab • Comprehensive Assessment Pack Page 2 of 2
