1206 Motion Unit

Motion Calculation

• Speed Calculation Formula:

  • Formula: Speed = Distance / Time

  • Example Calculation for Car:

    • Given Values: Distance = 45 m, Time = 15 s

    • Calculation: Speed = 45 m / 15 s = 3 m/s

Chapter 5 - Investigating Motion

Science vs Technology

• Science and technology serve different purposes despite often being used interchangeably.

• Scientists investigate natural and constructed worlds using specific processes.

• Engineers design and enhance technology to solve practical problems and fulfill human needs.

Approaches to Scientific Problems

Problem Classification

• Different approaches are used according to the nature of the inquiry.

• Classifying a question as scientific or technological requires distinct strategies.

Classification Exercise: Scientific vs Technological

Statements Classification:

• Scientific Questions (S) or Technological Problems (T):

  • Effect of headwind on an airplane's velocity? S

  • Modifying vehicle design for headwind? T

  • Increasing a car's acceleration? T

  • Force effect on car's acceleration? S

  • Improving passenger safety in a car? T

  • Modifying a fishing boat for more capacity? T

  • Effect of golf ball dimples on flight? S

Metric System and Conversion Factors

Overview

• The Metric System consists of base units and prefixes for easy measurement.

• Common SI prefixes:

  • Kilo (k): x10^3

  • Hecto (h): x10^2

  • Deca (da): x10^1

  • Deci (d): x10^-1

  • Centi (c): x10^-2

  • Milli (m): x10^-3

Conversion Method

Method One: Unit Factors

1. Identify given value and target units.

2. Establish a conversion factor using factors of 10.

3. Apply the conversion factor to calculate the desired unit.

Method Two: Decimal Movement

1. Identify given value and target units.

2. Move the decimal place according to the conversion factor distance:

   • Larger unit: move left

   • Smaller unit: move right

Practice Exercises: Metric Conversion

Examples:

• Convert 1241 m to km:

  • Conversion: 1241 m x (1 km/1000 m) = 1.241 km

• Convert 86 cm to hm:

  • Conversion: 86 cm x (1 hm/10,000 cm) = 0.0086 hm

Time Conversions

Key Facts:

• 1 minute = 60 seconds

• 1 hour = 60 minutes

• Use unit factors for time conversion as well.

Practice Problems: Time Calculations

1. Convert 17.3 minutes to seconds:

   • 17.3 min x 60 = 1038 s

Motion Conversion: Speed Transformations

km/h to m/s:

• To convert km/h to m/s, divide by 3.6.

Example:

• Convert 50 km/h to m/s:

  • 50 km/h ÷ 3.6 = 14 m/s

m/s to km/h:

• To convert m/s to km/h, multiply by 3.6.

Example:

• Convert 12 m/s to km/h:

  • 12 m/s x 3.6 = 43.2 km/h

Scientific Notation

Definition:

• Scientific notation simplifies large or small numbers to a base and exponent format.

Examples:

• 0.0034 m = 3.4 x 10^-3 m

Conversion Techniques:

• Greater than 1: Positive exponent

• Less than 1: Negative exponent

Error Types

Random Error:

• Variability in measurements; reduce through multiple readings.

Systematic Error:

• Consistent inaccuracies from instruments; maintain calibration.

Parallax Error:

• Variability due to position; minimize by aligning measurements properly.

Significant Figures:

• Represent the certainty of measurements.

Common Rules:

1. Non-zero digits are significant.

2. Zeros between non-zero digits are also significant.

3. Leading zeros are not significant.

4. Trailing zeros with a decimal point are significant.

5. Exact numbers have infinite significant figures.

Calculating Precision and Accuracy

Definitions:

• Accuracy: Closeness to true value.

• Precision: Exactness of measurement, such as consistency across repeated trials.

Error Calculation:

• Use absolute values to determine differences in measurements

Motion Calculations and Practice Problems

• Combined calculations incorporating distance, speed, velocity, and units.

• Apply significant figures appropriately to report answers clearly.