+0  
 
0
2923
3
avatar+546 

22) (equation) bake cake until the center is 180deg F; cool to 120degF

A-given room temp of 70deg what is an exponential model for this data.

B- how long does it take for the cake to cool to desired temp

 

 

28) find amount in a continuously compounded amount for the given conditions.

principal:$2000

annual interest rate: 5.1%

time: 3 years

 Aug 13, 2014

Best Answer 

 #1
avatar+129899 
+10

22)....I'm not a Physics major (or even minor!! ) but this one is based on Newton's Law of Cooling.......I don't believe we can answer the question unless we know how long it took for the center to cool from 180F to some lesser temperature.....we have to know this in order to find the constant of proportionality.....(Alan can correct me, if I'm wrong!!) ..also...is 120F the desired temperature??

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28)   This is given by     A = Pe(rt)   where A is the accumulated amount, P is the amount invested, r is the interest rate (as a decimal) and t is the time....so we have....

A = 2000e(.051*3) = about $2330.65

 

 Aug 13, 2014
 #1
avatar+129899 
+10
Best Answer

22)....I'm not a Physics major (or even minor!! ) but this one is based on Newton's Law of Cooling.......I don't believe we can answer the question unless we know how long it took for the center to cool from 180F to some lesser temperature.....we have to know this in order to find the constant of proportionality.....(Alan can correct me, if I'm wrong!!) ..also...is 120F the desired temperature??

----------------------------------------------------------------------------------------------------

28)   This is given by     A = Pe(rt)   where A is the accumulated amount, P is the amount invested, r is the interest rate (as a decimal) and t is the time....so we have....

A = 2000e(.051*3) = about $2330.65

 

CPhill Aug 13, 2014
 #2
avatar+12 
+5

T(t) = TA + (TH - TA)e-kt

where,

T(t) = Temperature at time t,
TA = Ambient temperature (temp of surrounding)
TH = Initial temperature of the cake
k = constant of proportionality (negative because of cooling)
t = time.

Now, for A, we have,

120 = 70 + (180 - 70)e-kt, or $$\frac{}{}$$e-kt = 5/11

For B, i.e. to find t, you need k.

 Aug 13, 2014
 #3
avatar+546 
0

this is just algebra CPHill. dont be so hard on yourself!

 Aug 13, 2014

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