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Gradients as rates of change

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शिक्षकों के लिए: Gradients as rates of change (Mathematics, Ratio, proportion and rates of change) के लिए इस्तेमाल के लिए तैयार लेसन स्लाइड्स, रिवीज़न नोट्स — इन्हें अपने लेसन में इस्तेमाल करें, या टॉपिक को एक इंटरैक्टिव क्लास एक्टिविटी की तरह चलाएं जिसे आपके शिक्षार्थी लाइव गेम की तरह खेलें।

लेसन नोट्स

The gradient as a rate

  • The gradient of a graph measures how fast y changes compared with x: \frac{\text{change in } y}{\text{change in } x}.
  • The units of the gradient are units of y per unit of x: for a distance–time graph, metres per second.

Straight-line graphs

  • A straight line has a constant rate of change. A line from (0, 2) to (4, 14) has gradient \frac{12}{4} = 3.
  • On a proportional currency-conversion graph, gradient is the example exchange rate in the plotted units. On a linear cost graph it is price per unit.

Curved graphs

  • A tangent has the same gradient as the curve at the chosen point. It can cross the curve at an inflection point or meet the curve elsewhere; its gradient gives the instantaneous rate.
  • The average rate of change between two points is the gradient of the chord joining them.

Average and instantaneous rates

Average and instantaneous ratesO510151234xytangent,m = 2Chordy = x² + 1

Interpreting graphs

  • Compare steepness only on the same scales. The magnitude of gradient measures rate magnitude; its sign records increase or decrease. A horizontal line shows no change.
  • Area under a rate graph gives the total change: the area under a speed–time graph is distance.

Real contexts

  • A volume–time graph has gradient equal to volumetric flow rate. For constant incoming volume per second, depth rises faster where the container has a smaller horizontal cross-sectional area.

स्लाइड्स

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प्रैक्टिस सवाल

फ्री प्रीव्यू — 32 में से 8 सवाल। सभी देखने के लिए साइन अप करें।
  1. 1.What does the gradient of cumulative distance travelled against time represent?

    Easy
    • Aspeed
    • Bdistance
    • Ctime
    • Dacceleration
  2. 2.A line passes through (0, 0) and (5, 20). What is the gradient?

    Easy
    • A4
    • B5
    • C0.25
    • D100
  3. 3.A line passes through (2, 3) and (6, 11). What is the gradient?

    Easy
    • A2
    • B4
    • C8
    • D0.5
  4. 4.An example proportional currency-conversion graph shows £10 = €12. What is the gradient in euros per pound?

    Easy
    • A1.2
    • B0.83
    • C12
    • D120
  5. 5.The gradient of a speed–time graph is 3 m/s². What does this mean?

    Easy
    • Ait accelerates at 3 m/s each second
    • Bit travels 3 m
    • Cit is at rest
    • Dspeed is constant
  6. 6.A horizontal line on a graph of temperature against time means:

    Easy
    • Atemperature is rising
    • Btemperature is falling
    • Ctemperature is constant
    • Dtemperature is zero
  7. 7.What are the units of the gradient of a graph of distance (km) against time (hours)?

    Easy
    • Akm/h
    • Bh/km
    • Ckm
    • Dhours
  8. 8.A graph of water volume (litres) against time (minutes) has gradient 5. What does it mean?

    Easy
    • A5 litres per minute
    • B5 litres in total
    • C5 minutes per litre
    • D5 minutes

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