# Animal Foraging Radius Equation Part 2

1. Nov 30, 2012

### killbot2000

1. The problem statement, all variables and given/known data

I asked a similar question before relating to an animal's foraging radius. I think there was a typo but I'd like to show another example to see if I'm on the right track.

The parameter values are as follows:

Q= 5.2 × 106 J
C = 1.5kg
d= 0.055kg per hour
k= 2.0 Joules/m
Ema = 24 Watts
Emc = 42 Watts
T = 48 hours
v= 45km per hour
t= 12 hours

2. Relevant equations

r = [QC +Qdt - T(Ema+Emc/2)/(2k+ (2Qd/v))]

3. The attempt at a solution

(7800000 + 5.2*10^6*.055*12 - 172800 (45))/16.711111111111112

2. Nov 30, 2012

### epenguin

A minor point is that it would be good practice to group the first two numerator terms as
Q(C + DT). One less arithmetical operation to do and error risked. Similarly you could take out the factor 2 in the denominator

More important is you must pay constant attention to units. E.g.you do not give a unit for your result - metres or Km...

It seems there is something wrong about your physical units, maybe misquotation of formulae or units? The expression I just gave is JoulesXKg. The way you have written the equation they appear as such in the result which is nonsense - you must get a distance. The denominator has a similar anomaly and you would be adding things of incompatible dimensions - it is probably the second term that is wrong.

3. Dec 2, 2012

### epenguin

(I see I drew attention to the same units and dimensions issue in your previous thread.)