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Phil is an athlete - Junior Cycle Mathematics - Question 2 - 2018
Question 2
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 not start at (0... show full transcript
Worked Solution & Example Answer:Phil is an athlete - Junior Cycle Mathematics - Question 2 - 2018
Step 1
(i) 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
From the graph, we can find the calorie burn for an average heart rate of 170 beats per minute. This corresponds to approximately 750 kcal per hour. Thus, the answer is:
Calories burnt in one hour = 750 kcal.
Step 2
(ii) Use the graph to work out Phil's average heart rate when she burns 300 kcal in 30 minutes.
Answer
If Phil burns 300 kcal in 30 minutes, that means she would burn 600 kcal in one hour. Referring to the graph, we find that this corresponds to an average heart rate of approximately 155 beats per minute. Therefore, the answer is:
Average heart rate = 155 beats per minute.
Step 3
Step 4
Work out Phil's average speed for this stage, in metres per second.
Answer
To find Phil's average speed for the stage, we first need to calculate the total distance and total time:
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Total distance = Slow run distance + Sprint distance = 60 m + 150 m = 210 m
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Total time:
- Slow run time = Distance / Speed = 60 m / 2 m/s = 30 seconds
- Sprint time = Distance / Speed = 150 m / 7.5 m/s = 20 seconds
- Total time = 30 seconds + 20 seconds = 50 seconds
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Average speed = Total distance / Total time = 210 m / 50 s = 4.2 m/s.
Thus, Phil's average speed for this stage is:
Average Speed = 4.2 m/s.