3. Quit Why have formulas? Area of disc Speed, Distance, Time E = mc 2 Changing the subject

4. Quit Formulas are designed to make maths easy. When presented with a new formula, learn what each letter stands for. Once this is known, the formula can be used. The important thing about formulas is to use them without worrying about where the formulas come from. This is what they are produced for. Why have formulas?

5. Quit  r  r r Area of disc =  r 2

6. Quit D S  T = 2 m/sec Speed = Distance Time = 10 5 Walk 10 metres (m) across the room in 5 seconds.

7. Quit E = m c 2 E = energy measured in joules (J) m = mass measured in kilogrammes (kg) c = speed of light measured in metres per second (m/s) Light moves at about 300,000 km/sec!

8. Quit –– Changing the subject of a formula Emc2c2 = Divide both sides by c 2 (m)(m)

9. Quit –– Changing the subject of a formula Emc= Divide both sides by m 2 Take the square root of both sides (c)(c)

10. Quit ––––– ( ) Changing the subject of a formula a + d e = Multiply both sides by u 2 Take 2f from both sides +2f2f u – Take the square root of both sides (e)(e)

11. Quit Changing the subject of a formula Take ut from both sides (a)(a) s = ut + at 2 1212 –

12. Quit Changing the subject of a formula Multiply both sides by 2 (a)(a) s – ut = at 2 1212 –

13. Quit Changing the subject of a formula Divide both sides by t 2 (a)(a) 2(s – ut) = at 2

14. Quit Changing the subject of a formula Multiply out top line (a)(a) ––––––– 2(s – ut) = a t 2t 2

15. Quit Changing the subject of a formula Simplify (a)(a) ––––––– 2s – 2ut = a t 2t 2

16. Quit Changing the subject of a formula (a)(a) t 2 t = a –– – –– 2s 2u

17. YesNo Do you want to end show?