1. Year 8: Compound Measures Dr J Frost (jfrost@tiffin.kingston.sch.uk) Last modified: 8 th June 2015Associated Resources: Yr8-SpeedDistanceTimeQuestions

2. Jessica Ennis ran her 0.8km Olympic heptathlon race in a time of 2:08.65. What was her average speed? Answer = 6.22m/s ? The formula relating speed-distance time: s d t The unit of speed might for example be m/s or kmph. How does the unit help us remember the formula? Starter

3. Quickfire Qs s d t SpeedDistanceTime 2m/s5s10m ? 5m/s4.8s24m ? 0.2km/s250s50km ? 5km/h7200s10km ?

4.   Jeremy Clarkson travels 250 miles at a constant speed of 100mph. How much time has elapsed? Answer: 2 hours 30 minutes Getting your units right! Hans Solo and Chewbacca activate their warp drive and travel at the speed of light. Light travels at a speed of 299792.458 km/s. What distance have they travelled after a year? 6,460,000,000,000,000m 9,460,000,000,000,000m 12,460,000,000,000,000m 15,460,000,000,000,000m  Choose Examples

5. The density of a rock is 2.75g/cm 3. Using the unit, can you guess the formula for density? ? This is a rock. Density

6. FROST MANOR Click for Catimation 10mph 20mph Considering total time/distance Pippin the cat runs to the end of my garden at 10mph and back at 20mph. What was her average speed? (Bro Tip: It helps to lay out your speed/distance/time information in a table) Period 1Period 2 Speed10 mph20 mph Distance20 miles Time2 hours1 hour ?? ?? ? Let’s set it arbitrarily for now. It won’t affect the answer.

7. FROST MANOR 10mph 20mph Considering total time/distance We could also do it algebraically to keep the distance general. Period 1Period 2 Speed10 mph20 mph Distance Time ? ? ? ? ?

8. Test Your Understanding Bob the Builder needs to travel to a building site. He drives the first part of the journey of 10 km at 20 km/h. The total journey time is 1 hour. What speed did he drive for the remainder of the journey if his average speed across the whole journey was 40 km/h? Papa Smurf walked 10m at 5 m/s from A to B, and then 5m at 10m/s from B to C. What was Papa Smurf’s average speed across the journey? A to BB to C Speed5m/s10 m/s Distance10m5m5m Time2 seconds0.5 seconds 1 st 2 nd Speed20 km/h Distance10 km Time0.5 hr Q  ? ? ? ?? ?

9. Take your pick: Activity Easier and MediumMedium and Difficult (Merits to anyone who gets both of the Difficult questions correct) E1) 33 minutes 20 seconds E2) 500g/cm 3 M1) 3.3kg M2) 38 laps D1) 25% D2) 2 ¼ hours ? ? ? ? ? ?

10. Exercises (on sheet) 27.2 km/h 12 mph 12 miles (a) 130m (b) 40cm (c) 300m Johnson 8 g/cm 3 12 g/cm 3 £1440 £9600 1 2 3 4 5 6 7 8 9 EasierHarder B 60mph D 2 1/3 mph E 13 1/3 miles 66 mph 25 m/s A 1 2 3 4 5 6 7 8 9 10 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?