Spring Scale Lab Worksheet
Physical Science Lab Guide Page 1 of 2
Spring Scale Mechanics
Force Units, Scale Calibration, and Push vs. Pull Measurement
Name:
Date:
Period:
Scale Range:
Part 1: The Anatomy of a Force Gauge
1. Forces and the Newton (N): A force is a push or pull. Scientists measure force in Newtons (N). Unlike mass (grams or kilograms, measuring matter), force measures an active interaction. On Earth, gravity exerts approximately \(1\text{ N}\) of downward force on a \(100\text{g}\) mass (about the weight of a medium apple).
2. How Springs Measure Force (Hooke's Law): Inside the scale is a calibrated spring. When pulled or pushed, the spring stretches or compresses in direct proportion to the applied force. If \(1\text{ N}\) stretches a spring \(1\text{ cm}\), a \(2\text{ N}\) force will stretch it exactly \(2\text{ cm}\).
3. Measuring Push Forces & Zeroing: Standard spring scales measure tension (pull). However, push-type scales use an internal compression spring or a rigid sliding rod. Pressing the front bumper against an object compresses the spring and moves the indicator. Before any measurement, turn the top calibration nut until the indicator aligns exactly with \(0\text{ N}\) to avoid zero-point error.
Scale Diagram
Zero Nut
g N
0 0.0
100 1.0
240 ▶ POINTER 2.4
300 3.0
500 5.0
Push Bumper
0–5 N Push Gauge
Part 2: Concept Check & Measurement Reasoning (5 Questions)
1. Force vs. Mass: Why must push force be recorded in Newtons (N) rather than grams (g)?
2. Diagram Reading: Each small division on the diagram scale represents \(0.1\text{ N}\). What value is indicated by the pointer?
Reading: ____ N
3. Calibration: What is "zero-point error", and how does turning the calibration nut correct it?
4. Internal Mechanics: What happens to the internal spring during a push force versus a pull force?
5. Force Application: You push a block at constant, steady speed across a desk with a scale reading of \(1.6\text{ N}\). How much friction force opposes the push? Explain your reasoning.
Check that zero calibration is verified before starting the investigation. Turn to Page 2 for Hands-on Push Lab ➔
Hands-On Laboratory Investigation Page 2 of 2
Part 3: Measuring Applied Push Force
Objective: Measure and record the peak static push force to initiate motion and the kinetic push force needed to maintain steady motion across different surfaces.
Standardized Push Protocol
Warning: Keep scale parallel to the surface!
Step 1: Horizontal Zeroing
Lay the scale flat on the testing table. Turn the calibration nut until the indicator aligns with \(0\text{ N}\) in horizontal position.
Step 2: Static Push (Peak)
Press the push bumper against the object. Increase force slowly. Record the peak force right before the object begins to slip.
Step 3: Kinetic Push (Constant)
Keep pushing smoothly at a slow, constant speed across \(20\text{ cm}\). Observe and record the steady force value.
Push Force Data Log Record all measurements in Newtons (N)
| Test Object & Surface | Predicted (N) | Trial 1 (N) | Trial 2 (N) | Trial 3 (N) | Avg. Static | Steady Kinetic |
|---|
| 1. Textbook on Smooth Desk | | | | | | |
| 2. Textbook on Paper Towel / Cloth | | | | | | |
| 3. Wooden Block / Pencil Case | | | | | | |
| 4. Compress Sponge or Foam | | | | | | |
| 5. Student Choice: ______________ | | | | | | |
Part 4: Data Analysis & Measurement Reasoning (Grades 6–8 Depth)
1. Static vs. Kinetic Comparison: Compare your average static push force to your steady kinetic push force for the textbook. Which was greater, and what physical reason explains this?
2. Systematic Alignment Error: If you pushed the scale downward at an angle instead of holding it flat and parallel to the desk, how would that distort the force reading?
3. Instrument Resolution & Uncertainty: What is the smallest increment mark on your scale? How does this resolution limit the precision of your measured data?
Key Takeaway: In steady constant motion, \(F_{\text{push}} = F_{\text{friction}}\). Your push scale directly quantifies the opposing resistive force!
Physical Science Lab • Force & Measurement Lab Handout Complete
