Lower Secondary Science - Speed
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Questions and Answers

What is the SI unit used to measure area?

  • m3
  • m2 (correct)
  • kg
  • m/s
  • Which of the following is NOT considered a base quantity?

  • Mass
  • Area (correct)
  • Length
  • Temperature
  • How is speed defined in terms of base quantities?

  • metres - seconds
  • metres + seconds
  • metres x seconds
  • metres / seconds (correct)
  • Which of these base quantities is represented by the symbol 'A'?

    <p>Ampere</p> Signup and view all the answers

    What is the SI unit for volume?

    <p>m3</p> Signup and view all the answers

    Which of the following base quantities defines mass?

    <p>kg</p> Signup and view all the answers

    Which derived quantity is represented by the formula 'metres x metres x metres'?

    <p>Volume</p> Signup and view all the answers

    Which of the following is true regarding derived quantities?

    <p>They can be represented using base quantities.</p> Signup and view all the answers

    What is the prefix for a factor of $10^{-3}$?

    <p>m</p> Signup and view all the answers

    How many millimeters are in one centimeter?

    <p>10 mm</p> Signup and view all the answers

    Which prefix corresponds to a factor of $10^{6}$?

    <p>M</p> Signup and view all the answers

    What is the equivalent of 0.36 kg in grams?

    <p>360 g</p> Signup and view all the answers

    What is the formula for calculating average speed?

    <p>Average speed = Total distance travelled / Total time taken</p> Signup and view all the answers

    What is the prefix for a factor of $10^{-2}$?

    <p>c</p> Signup and view all the answers

    Which statement correctly distinguishes average speed from instantaneous speed?

    <p>Average speed is based on total distance and total time, while instantaneous speed is speed at a particular moment.</p> Signup and view all the answers

    How many seconds are in 2.4 hours?

    <p>8640 s</p> Signup and view all the answers

    What is the equivalent of 75 meters in millimeters?

    <p>7500 mm</p> Signup and view all the answers

    What can be deduced from a distance-time graph when the line is horizontal?

    <p>The object is at rest.</p> Signup and view all the answers

    Which of the following is NOT a base quantity in the International System of Units?

    <p>Speed</p> Signup and view all the answers

    Which of the following is not a valid prefix used in scientific measurements?

    <p>p</p> Signup and view all the answers

    What does the slope of a speed-time graph represent?

    <p>Acceleration of the object</p> Signup and view all the answers

    When measuring length, which of these instruments would ensure the most accurate measurement?

    <p>Calipers</p> Signup and view all the answers

    What is an effect of systematic errors in measurements?

    <p>They lead to consistent bias in measurements.</p> Signup and view all the answers

    Which of the following represents a unit of length in the International System of Units?

    <p>Metre</p> Signup and view all the answers

    What is the formula for calculating average speed?

    <p>Total Distance / Total Time</p> Signup and view all the answers

    Which method traditionally measures the speed of an object during a school sports day?

    <p>Tape and stopwatch</p> Signup and view all the answers

    What does a speedometer measure?

    <p>Instantaneous speed</p> Signup and view all the answers

    Why can't the method of using a stopwatch measure varying speeds during a race?

    <p>It cannot track speed changes at intervals.</p> Signup and view all the answers

    What is the typical range of a speedometer in a car?

    <p>0 to 200 km/h</p> Signup and view all the answers

    What type of speed is measured when time and distance are not specified?

    <p>Average speed</p> Signup and view all the answers

    How is instantaneous speed typically expressed by a speedometer?

    <p>km/h</p> Signup and view all the answers

    What is the primary limitation of measuring speed using a tape and stopwatch?

    <p>Inability to measure speed accurately.</p> Signup and view all the answers

    What does the point (0,0) on a speed-time graph represent?

    <p>A body at rest</p> Signup and view all the answers

    Which segment of a speed-time graph indicates a constant speed?

    <p>Segment BC</p> Signup and view all the answers

    During which segment does the speed of the car decrease?

    <p>Segment CD</p> Signup and view all the answers

    At what time does the car reach its maximum speed?

    <p>t = 2 s</p> Signup and view all the answers

    What is the instantaneous speed of the car at t = 1 s?

    <p>2.5 m/s</p> Signup and view all the answers

    Which segment of the graph indicates increasing speed?

    <p>Segment AB</p> Signup and view all the answers

    What characteristic defines the motion during segment BC?

    <p>Speed is constant</p> Signup and view all the answers

    When analyzing speed-time graphs, which point typically indicates maximum acceleration?

    <p>The steepest slope on the graph</p> Signup and view all the answers

    Study Notes

    Units and Physical Quantities

    • The International System of Units (SI) was established in 1968 as a universal set of measurement units.
    • Physical quantities consist of a numerical magnitude and a unit; measurements without units are meaningless.

    The 7 Base Units

    • Length: metre (m)
    • Time: second (s)
    • Mass: kilogram (kg)
    • Electric Current: ampere (A)
    • Thermodynamic Temperature: kelvin (K)
    • Amount of Substance: mole (mol)
    • Luminous Intensity: candela (cd)

    Derived Units

    • Area: square metres (m²)
    • Volume: cubic metres (m³)
    • Speed: metres per second (m/s)

    Measurement Skills

    • Estimation and measurement of length are crucial skills, requiring tools like measuring tapes and calipers.
    • Time intervals for moving objects can be determined using stopwatches and video analysis.
    • Precision and accuracy in measurements must consider errors like parallax.

    Speed Concepts

    • Speed is defined as the distance traveled per unit time.
    • Average speed formula: Average speed = Total distance / Total time.
    • Instantaneous speed refers to speed at a specific moment.

    Graph Analysis

    • A distance-time graph shows:

      • At rest: horizontal line
      • Uniform speed: straight diagonal line
      • Non-uniform speed: curved line
    • A speed-time graph shows:

      • At rest: horizontal line at zero
      • Uniform speed: horizontal line above zero
      • Increasing speed: rising line
      • Decreasing speed: falling line

    Prefixes and Scientific Notation

    • Common prefixes for multiples and sub-multiples include:
      • kilo (k) = 10³
      • mega (M) = 10⁶
      • giga (G) = 10⁹
      • milli (m) = 10⁻³
      • micro (µ) = 10⁻⁶
      • nano (n) = 10⁻⁹

    Speed Measurement Techniques

    • Traditional methods: measured using a tape and stopwatch for average speed.
    • Modern methods: speedometers provide instantaneous speed readings, often in km/h.

    Example Calculations

    • Conversion factors:
      • 1 cm = 10 mm
      • 1 m = 100 cm
      • 1 km = 1,000 m
    • Instantaneous speed can be determined at specific time points based on graph data.

    Motion Description

    • Speed changes can be analyzed over time:
      • For instance, a car's speed can increase, remain constant, or decrease, reflecting different segments of a journey.

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    Description

    Test your understanding of key concepts in transportation science, including units of length, time, speed, and how to interpret distance-time and speed-time graphs. This quiz focuses on cognitive skills related to physical quantities and their appropriate SI units.

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