---
title: "Ruler — AP Physics 1 Definition & Lab Measurement Guide"
description: "A ruler is a straight tool for measuring length or distance. In AP Physics 1, it shows up in experimental design FRQs where you pick tools and justify precision."
canonical: "https://fiveable.me/ap-physics-1-revised/key-terms/ruler"
type: "key-term"
subject: "AP Physics 1"
---

# Ruler — AP Physics 1 Definition & Lab Measurement Guide

## Definition

A ruler is a straight, flat tool used to measure the length or distance between two points.

## Related Study Guides

- [Unit 4 FRQ (Energy) Answers](/ap-physics-1-revised/unit-Udr75ggSrboDhyB7/unit-4-frq-energy-answers/study-guide/uTQcMXz4kiUk6BoHiOwH)

## Review

### Related Terms

- Tape Measure: A flexible measuring tool that can be used to measure longer distances.
- Caliper: A precise measuring instrument used to measure small distances or thicknesses.
- [Scale](/ap-physics-1-revised/key-terms/scale): A device that measures weight or mass.