Teacher's notes and answers to questions in the book - Hodder Plus ...

WJEC GCSE Additional Science Teacher’s Notes
15
Distance, speed and
acceleration
_ Measuring speeds (pages 165–67)_______________
TASK The animal olympics 100 m final (pages 166–67)
1. Each animal finishes the 100 m race. Use the data to calculate the times for each competitor.
Animal
Top speed Distance
(m/s) travelled (m)
Time (s)
Cheetah 31 100 3.2
Pronghorn antelope 27 100 3.7
Lion 22 100 4.5
Springbok 22 100 4.5
Horse 21 100 4.8
Elk 20 100 5.0
Coyote 19 100 5.3
Usain Bolt 19 100 5.3
2. Explain why, in reality, the times for each competitor will be higher than those that you have
calculated.
The animals (and Usain Bolt) do not run at top speed for the whole race, they start at 0 m/s
and accelerate to top speed.
3. Usain Bolt broke the World 100 m record in the Beijing Olympic final in 2008, and this record
breaking run has been one of the most closely analysed runs in history, although he subsequently
broke his own world record in the 2009 World Championships. Usain Bolt’s mean times for the 2008
final race were as shown in Table 15.2.
a Make a copy of this table, but add a third column labelled ‘Average speed, m/s’. Calculate Usain
Bolt’s mean speed for each 10 m segment of the race and fill in your table.
Distance (m)
Split time (s)
Average speed in
segment (m/s)
Reaction time to leave blocks 0.165 0.0
0–10 (including reaction time) 1.85 5.4
10–20 1.02 9.8
20–30 0.91 11.0
30–40 0.87 11.5
40–50 0.85 11.8
50–60 0.82 12.2
60–70 0.82 12.2
70–80 0.82 12.2
80–90 0.83 12.0
90–100 0.90 11.1
0–100 9.69 10.3
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