Question

Assuming a typical efficiency for energy use by the body, how many slices of pizza must you eat to walk for 2.5 h at a speed of 5.0 km/h? Assume that your mass is 68 kg, metabolic power of 68 kg individual walking at 5 km/h is 380 W, and the energy content of slice of pizza is 1260 kJ.

Answer 1

Answer:

2.7 Pizzas.

Explanation:

The power required to walk through 5km in 1 hour is 380W.

A watt is basically Jules per second, then we need to standardized this measurement to second.

5km/hr is equal to,

$\frac{5km}{hr}*\frac{1hr}{3600s}*\frac{1000m}{1km}=1.389m/s$

Walking by 2.5 hours is equal to a distance of,

$d=v*t=1.389*(2.5*3600) = 12500m$

The total energy required then would be,

$E = \frac{380J}{1.389m/s}(12500)=3.4199*10^6J$

Then we know that one pizza slice gives $1260*10^3J$ of energy, the total pizza needed are,

$\eta = \frac{3.4199*10^6}{1260*10^3} = 2.7142$

Then you need to buy 3 pizza.