Maximizing Energy Usage: Swimming vs. Fast Food Meal

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In summary, a 68 kg person would need to swim at a fast crawl for approximately 1.77 seconds to use all the energy available in a typical fast food meal of burger, fries, and a drink, assuming 25% efficiency. This can be calculated by setting up the equation 5670 kJ * 0.25 = 800 W * time, and solving for time in seconds.
  • #1
KatlynEdwards
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Homework Statement



For how long would a 68 kg person have to swim at a fast crawl to use all the energy available in a typical fast food meal of burger, fries, and a drink? Assume 25% efficiency.

Homework Equations



Fast food meal provides 1350 Cal or 5670 kJ
A 68 kg person swimming at a fast crawl uses 800 W of metabolic power.

The Attempt at a Solution



I'm having trouble just setting up the equation.
I know that Change in Thermal Energy + Change in Chemical Energy = 0 because it is an isolated system, but I don't know where to go from here, nor do I know what units I need each part to be in.
 
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  • #2
Well, just think about this question for a second. This person intakes a certain amount of energy by eating the food. 25% of that energy is useable. The person then performs some activity that takes a certain amount of energy per second (or 800 J per second). You should be able to determine how long the person can swim just by giving the question some thought.
 
  • #3
So would it be 5670*.25=800W* time?

Solving for time gives me 1.77 - but what units is this?
 
  • #4
Op never mind, I needed to change kJ into Joules, then it gives me time in seconds. Whoops. :D
 

Related to Maximizing Energy Usage: Swimming vs. Fast Food Meal

1. How much energy can be obtained from a fast food meal?

The amount of energy that can be obtained from a fast food meal varies depending on the specific meal and its ingredients. However, on average, a fast food meal can provide around 800-1500 calories of energy.

2. Is the energy from a fast food meal healthy?

The energy from a fast food meal is typically high in calories, fat, and sugar, which can contribute to health issues such as obesity and heart disease if consumed in excess. It is important to balance fast food meals with healthier options and to consume them in moderation.

3. How is the energy from a fast food meal produced?

The energy from a fast food meal is produced through the breakdown of carbohydrates, fats, and proteins in the digestive system. These nutrients are then converted into a form of energy that the body can use for various functions.

4. Can the energy from a fast food meal be used for physical activity?

Yes, the energy from a fast food meal can be used for physical activity. However, it is important to note that fast food meals may not provide the necessary nutrients and fuel for sustained physical activity and may lead to fatigue or other health issues.

5. How does the energy from a fast food meal compare to other sources of energy?

The energy from a fast food meal is typically high in calories and provides a quick source of energy. However, it is important to note that whole, nutrient-dense foods such as fruits, vegetables, and lean proteins provide more sustainable and beneficial sources of energy for the body.

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