If the air temperature is the same as the temperature of your skin (about 30 ∘c), your body cannot get rid of heat by transferring it to the air. in that case, it gets rid of the heat by evaporating water (sweat). during bicycling, a typical 71.0 kg person’s body produces energy at a rate of about 502 w due to metabolism, 82.0 % of which is converted to heat. [recall that the normal internal body temperature is 98.6 ∘f and the specific heat capacity of the body is 3480 j/(kg⋅∘c) .] how many kilograms of water must the person's body evaporate in an hour to get rid of this heat? the heat of vaporization of water at body temperature is 2.42 \times 10^6\; {\rm j/kg}.the evaporated water must, of course, be replenished, or the person will dehydrate. how many 750 {\rm ml} bottles of water must the bicyclist drink per hour to replenish the lost water? (recall that the mass of a liter of water is 1.00 {\rm kg}.)

m=0.612kg

0.8164 bottles

Explanation:  the last part of the question says

How many kilograms of water must the person's body evaporate in an hour to get rid of this heat? The heat of vaporization of water at body temperature is 2.42 \times 10^6\;{\rm J/kg}.The evaporated water must, of course, be replenished, or the person will dehydrate. How many 750 {\rm mL} bottles of water must the bicyclist drink per hour to replenish the lost water? (Recall that the mass of a liter of water is 1.00 {\rm kg}.)

Convert 500 watts to joules/sec.

That is 500 J/sec. The problem states about 80% is converted to heat so 500 J/sec x 0.8 = ?? heat produced in 1 sec.

How many J is that per hour.

502 J/sec x (60 sec/min) x (60 min/hour)

1807200J

Rcallit is 82% efficient

1481904J

q=mlv

q=heat produced by the body in Joules

m=mass of water loss

lv=latent eat of vaporization in

1481904J=m*2.42*10^6j/kg

m=0.612kg

the same as 0.612L

0.612l/0.750L/bottle

0.8164 bottles

russian is not my first language, so i'm afraid i can't write out an answer in russian, but hopefully you can find a way to do so. here's my best translation of the problem: you're given a plot of a particle's position in one-dimensional space over time, and you're asked to find either the total distance traveled by the particle after 6 seconds had elapsed, or the total displacement of the particle after 6 seconds.

if you want the total distance traveled, you would first need to determine the particle's velocity as a function of time, then integrate that over the 6-second interval. we know the position function is quadratic with roots at 0 and 6, so we have

where is unknown. because the position is parabolic, there is symmetry about the midpoint at , and we know that

so that the position function is

which means the velocity is

then the total distance traveled is

so the total distance traveled is 20 m.

on the other hand, if you want to find displacement: the particle starts at and ends at , so its displacement is 0.

where is the