BIO Should You Walk or Run? It is 5.0 km from your home to the physics lab. As part of your phys

step 1 In the given problem, the total distance between home to the physics lab is given as 5 km. So he

BIO Should You Walk or Run? It is 5.0 km from your home to...

BIO Should You Walk or Run? It is 5.0 $\mathrm{km}$ from your home to the physics lab. As part of your physical fitness program, you could run that distance at 10 $\mathrm{km} / \mathrm{h}$ (which uses up energy at the rate of 700 $\mathrm{W}$ ), or you could walk it leisurely at 3.0 $\mathrm{km} / \mathrm{h}$ (which uses energy at 290 $\mathrm{W}$ W). Which choice would burn up more energy, and how much energy (in joules) would it burn? Why is it that the more intense exercise actually burns up less energy than the less intense exercise?

Key Concepts

Intensity vs Duration Trade-off

The trade-off between exercise intensity and duration is an important concept in energy expenditure. A high-intensity activity, while using energy more rapidly, may be performed for a shorter time, resulting in less total energy burned. Conversely, a lower-intensity exercise, performed over a longer period, can result in a higher overall energy consumption despite the lower rate of energy use.

Unit Conversion (Watt to Joules)

Understanding that one watt is equal to one joule per second is crucial when calculating energy consumption. By converting the time spent exercising into seconds and multiplying by the power in watts, one can determine the total energy burned in joules.

Power

Power is the rate at which energy is expended or work is done, typically measured in watts (W), which are equivalent to joules per second (J/s). In the context of physical exercise, it reflects how quickly your body uses energy.

Total Energy Consumption (Work = Power × Time)

The total energy consumed during an activity is calculated by multiplying the power used by the duration of the activity. This concept is fundamental because even if one exercise mode has a higher power output (i.e., is more intense), a shorter duration of exercise can result in lower overall energy expenditure compared to a less intense, longer-duration activity.

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