Rate of change of linear functions
Burning calories
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The food we eat provides our body with energy,
which is measured in calories. When we are physically
active, our bodies burn energy at a much higher rate than when we are at rest.
When we eat food containing more calories than the amount
our body burns, the unused energy is stored in body fat, and we
gain weight (each 7700 unburnt calories increase our body weight by
one kilogram).
Physical exercise helps people burn all the
calories they eat and maintain a steady body weight, or
burn more calories than they eat and lose weight when
needed. (Physical exercise has many other health benefits as well.)
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The number of calories the body burns during
physical exercise depends on the type of exercise, on how long one exercises, and on the
body weight of the person doing the exercise.
The figure below shows the number of
calories the body burns for several types of physical
exercise.
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calories burnt |
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Which are the activities that burn calories at the highest and lowest rates? Order the activities by
the rate at which they burn calories and explain how you did it.
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Investigate the effect of a person's weight on the calorie-burning rate.
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Ralph plays basketball for an hour on Sundays, Tuesdays, and Thursdays.
On the other days he wants to go for a run and wants to burn
the same amount of calories he burns during the
basketball games. How many kilometers should he run?
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Sara and Daniel go for a 45 minute walk every evening.
Sara weighs 50 kg, Daniel 75 kg. How
many calories does each burn during the walk?
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Alex is a bank teller who sits all day at work
and wants to engage in some physical activity in the
evenings to burn 250 clories. He weighs 70 kg.
What can you recommend for him?
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Ricky is a college student who weighs 60 kg. She wants
to design a daily exercise plan that includes
swimming in the morning and biking
in the evening. She wants to burn 300 calories a
day. What can you recommend for her?
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