They expend more oxygen. Littler endotherms lose warmth to the earth proportionately speedier than huge endotherms: less warm mass, protecting layers in littler creatures are less successful by dint of being more slender, and more prominent surface region to volume proportion implies snappier radiation of warmth
The equation for kinetic energy is,
Ke = (1/2)mv^2.
You're given a kinetic energy of 790 joules, and a speed of 1.6 m/s. Plugging these values into the equation, we get,
790 = (1/2)(1.6)^2(m).
Solving for m, we get,
m = (790)/(0.5(1.6)^2).
I'll let you crunch out those numbers for yourself :D
If you have any questions, feel free to ask. Hope this helps!
Density is directly proportional to mass. So if there's less matter inside object, its density will also reduce.