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Unit 21 Formula

Unit 21 Formula. Unit 21 Formula. 21.1 Using Formula. 4cm. w. 8 cm. l. Question What are the perimeter length and area if and ?. The perimeter length, P , and area, A , of a rectangle are given by the formulae where l is the length and w the width of the rectangle.

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Unit 21 Formula

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  1. Unit 21Formula

  2. Unit 21Formula 21.1 Using Formula

  3. 4cm w 8 cm l Question What are the perimeter length and area if and ? The perimeter length, P, and area, A, of a rectangle are given by the formulae where l is the length and w the width of the rectangle. Solution (a) Solution (b) ? ? ? ? ? ? ? ?

  4. Unit 21Formula 21.2 Constructing Formula

  5. When repairing air conditioning systems, an emergency engineer charges a basic fee of J$3000 plus J$1200 per hour. Question What does the engineer charge in total if the repair takes 6 hours? Question Find a formula for calculating the engineer's charge for repair work which takes n hours. Solution C = J$3000 + J$1200 × 6 C = J$3000 + J$7200 C = J$10200 Solution Let C = Charge So C = fixed charge + hourly charge × no. of hours C = J$3000 + J$1200 × n C = J$3000 + J$1200n ? ? ? ? ? ? ? ? ?

  6. Unit 21Formula 21.3 Negative Numbers

  7. Rules to remember Calculate 4 + (−10) = −6 −6 + 8 = 2 −4 − 5 = −9 −6 + (−7) = −13 (−40) ÷ (5) = −8 (−24) ÷ (3) = −8 (−40) ÷ (−5) = 8 (−6) × 7 = −42 ? ? ? ? ? ? ? ?

  8. Unit 21Formula 21.4 Temperature Differences

  9. What is the difference in temperature between Use information given on the above to answer these questions. Kingston and Singapore 4 Kingston and London 25 Kingston and Vancouver 29 London and New York 3 London and Sydney 26 Lima and Kingston 0 Oslo and Kingston 30 Moscow and Kingston 34 ? ? ? ? ? ? ? ?

  10. Unit 21Formula 21.5 Substitution in Formula

  11. l = (40 + 0.02T) cm Question What is the length of the rod when (a) T = 50˚C (b) T = −10˚C The length of a metal rod changes with temperature according to formula above; where T is the temperature in ˚C (a)l = (40 + 0.02 x 50) cm = (40 + 1) cm = 41cm Solution (b) l = (40 + 0.02 x −10) cm = (40 + −0.2) cm = 39.8cm ? ? ? ? ? ?

  12. Unit 21Formula 21.6 More Complex Formula

  13. The formula gives the focal length f for a lens Question What is the value of f, if u= 10cm and v = 8cm Solution ? ? ? ? ? ? Hence

  14. Unit 21Formula 21.7 Changing the Subject

  15. The formula that connects ˚Celsius (C) and ˚Fahrenheit (F) is Question Rewrite the formula in the form C = ...... Solution Take 32 from both sides of the formula So ? Multiply by 5 throughout ? Divide by 9 throughout ?

  16. Unit 21Formula 21.8 Pendulums

  17. The period of revolution, T, of a pendulum of length l is given by the formula when G is a constant. Solution Divide both sides by to give Problem Make l the subject of this equation. ? Square both sides ? ? Multiply both sides by G to give ?

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