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2 years ago

julie runs 1 and 1/2 miles in 1/3 hour.if julie continues to run at this speed,how many miles will she run per hour

Mathematics

2 answers:

NARA [144]2 years ago

5 0

She runs 4 1/2 miles an hour (I think..)

stira [4]2 years ago

3 0

20 miles per hour I'm almost completely positive

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Newton's law of cooling states that the temperature of an object changes at a rate proportional to the difference between its te

Aleonysh [2.5K]

Answer:

t=5.18 minute

Step-by-step explanation:

Using Newton's law of cooling

$\frac{dT}{dt}=-k(T-T_{s})$

T is temperature of a cup of coffee at any time t $T_{s}$ , is the temperature of the surrounding and k is a constant of proportionality in this negative because temperature is decreasing.

$T(0)=190\\T(1)=170\\T_{s}=66$

$\frac{dT}{dt}=-k(T-T_{s})\\\frac{dT}{(T-T_{s})}=-k*dt\\\int\limits {\frac{1}{T-T_{s} } } \, dT=-\int\limits {k} \, dt\\ln(T-T_{s})=k*t+C\\e*ln(T-T_{s})=e^{k*t+C} \\T-T_{s}=e^{k*t}*e^{C}\\e^{C}=C\\T-T_{s}=e^{k*t}*C\\T=T_{s}+e^{k*t}*C$

To find constant knowing the time and the temperature the first step of the change of energy in cup of coffee

$T=T_{s} +e^{-k*t}*C\\ C=190-66=124\\170=66+124*e^{-k*2}\\ 170-66=124*e^{-k*2}\\ln(\frac{104}{124})=ln*e^{-k*2}\\-0.175=-k*2\\k=0.08794$

Now using the constant of decreasing can find the time to be a 145 temperature the cup of coffee

$145=66+124*e^{-k*t} \\145-66=124*^{-0.087*t}$

$ln(0.637)=ln*e(-0.087*t)\\-0.45=-0.087*t\\t=5.18minutes$

4 0

3 years ago

What is 0.25% of 137

rodikova [14]

Answer:

0.342

Step-by-step explanation:

5 0

2 years ago

Read 2 more answers

A number added to 3 is equal to negative 5, find the number

anzhelika [568]

Answer:

-8

Step-by-step explanation:

An equation at represents this situation is:

-5 = 3 + x

Find x by;

-5 - 3 = -8

So x is -8:

-5 = 3 + -8 (TRUE)

Hope this helps

6 0

2 years ago

Read 2 more answers

Which of the following tables shows the correct steps to transform x^2+6x + 8=0

Vlad1618 [11]

Perhaps the most concise way to factor is by "completing the square" which is how the quadratic formula is derived...

x^2+6x+8=0 move constant to other side, subtract 8 from both sides

x^2+6x=-8, halve the linear coefficient, square it, then add that to both sides, in this case (6/2)^2=3^2=9

x^2+6x+9=1 now the left side is a perfect square of the form

(x+3)^2=1 take the square root of both sides

x+3=±√1 subtract 3 from both sides

x=-3±√1

x=-3±1

x=-4 and -2

Since the zeros occur when x=-4 and -2 the factors of the equation are:

(x+2)(x+4)

7 0

3 years ago

Rearrange the formula V = 1 3 πr2h for h. A) h = 3V πr2 B) h = V 3πr2 C) h = 3πr2 V D) h = πr2 3V

stiks02 [169]

Answer:

Option a) $h=\frac{3V}{\pi r^{2} }$

Step-by-step explanation:

The given formula seems to represent the volume of right circular cone. The correct formula is:

$V=\frac{1}{3} \pi r^{2} h$

We have to rearrange the formula for h. This means we have to move h on one side of the formula and all the other variables and constants on the other side of the equation. This can be done as shown below:

$V=\frac{1}{3} \pi r^{2} h\\\\3V=\pi r^{2} h\\\\h=\frac{3V}{\pi r^{2} }$

5 0

3 years ago