Ratio r: 2:1 RPM: 8 t: 20:10 R: 8:16 RPM: 16 Teeth: 20 Radius: 2

24 teeth 120 teeth 24 : 120 1 : 5 Which takes longest to complete a turn? Which has the greatest rpm? The large cog turns once in a minute. How many turns does the small cog make in this time? 5 : 1

0.8 : 0.2 : 0.3 4.2 : ? : ? Radius = 0.8m Radius = 0.2m 4.2 seconds per full turn ? seconds per full turn Radius = 0.3m 0.8 : 0.2 : 0.3 4.2 : ? : ? ? seconds per full turn

0.8 : 0.2 : 0.3 4.2 :1.05: ? Radius = 0.8m Radius = 0.2m 4.2 seconds per full turn 1.05 seconds per full turn Radius = 0.3m 0.8 : 0.2 : 0.3 4.2 :1.05: ? ? seconds per full turn

0.8 : 0.2 : 0.3 4.2 :1.05:1.575 Radius = 0.8m Radius = 0.2m 4.2 seconds per full turn 1.05 seconds per full turn Radius = 0.3m 0.8 : 0.2 : 0.3 4.2 :1.05:1.575 1.575 seconds per full turn

To calculate rpm from turn time: If a wheel takes 30 seconds to make one turn, it is running at a speed of 2 rpm (it turns twice in one minute) If it takes 5 seconds to turn, the speed is 12 rpm To calculate rpm from turn time: 60 ÷ time