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Question 2 (a) Phil is an athlete - Junior Cycle Mathematics - Question 2 - 2018
Question 2
Question 2 (a) Phil is an athlete. The graph below shows the number of calories (in kcal) she burns per hour, depending on her average heart rate. Note: the axes do... show full transcript
Worked Solution & Example Answer:Question 2 (a) Phil is an athlete - Junior Cycle Mathematics - Question 2 - 2018
Step 1
Use the graph to estimate how many calories Phil would burn in one hour if she had an average heart rate of 170 beats per minute.
Answer
To estimate the calories burned at 170 beats per minute, we locate the point on the graph corresponding to this heart rate. At 170 beats per minute, the graph shows that Phil would burn approximately 750 kcal in one hour.
Step 2
Use the graph to work out Phil’s average heart rate when she burns 300 kcal in 30 minutes.
Answer
Since 300 kcal in 30 minutes is equivalent to 600 kcal in one hour, we refer back to the graph. At 600 kcal burned per hour, Phil's average heart rate can be estimated as approximately 155 beats per minute.
Step 3
Step 4
Work out Phil’s average speed for this stage, in metres per second.
Answer
To calculate average speed, we use the formula:
ext{Average Speed} = rac{ ext{Total Distance}}{ ext{Total Time}}For the slow run, the time taken is:
For the sprint, the time taken is:
Total time = 30 seconds + 20 seconds = 50 seconds.
Total distance = 60 m + 150 m = 210 m.
Then, average speed is: ext{Average Speed} = rac{210 ext{ m}}{50 ext{ s}} = 4.2 ext{ m/s}