Calculus 1 : Rate of Change

Study concepts, example questions & explanations for Calculus 1

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Example Questions

Example Question #661 : How To Find Rate Of Change

A cube is growing in size. What is the ratio of the rate of growth of the cube's volume to the rate of growth of its sides when its sides have length 30?

Possible Answers:

\(\displaystyle 900\)

\(\displaystyle 2700\)

\(\displaystyle 5400\)

\(\displaystyle 8100\)

\(\displaystyle 90\)

Correct answer:

\(\displaystyle 2700\)

Explanation:

Begin by writing the equations for a cube's dimensions. Namely its volume in terms of the length of its sides:

\(\displaystyle V=s^3\)

The rates of change of the volume can be found by taking the derivative of each side of the equation with respect to time:

\(\displaystyle \frac{dV}{dt}=3s^2\frac{ds}{dt}\)

Now, knowing the length of the sides, simply divide to find the ratio between the rate of change of the volume and sides:

\(\displaystyle 3s^2\frac{ds}{dt}=(\phi)\frac{ds}{dt}\)

\(\displaystyle \phi=3s^2\)

\(\displaystyle \phi =3(30)^2=2700\)

Example Question #662 : How To Find Rate Of Change

A cube is growing in size. What is the ratio of the rate of growth of the cube's volume to the rate of growth of its sides when its sides have length 32?

Possible Answers:

\(\displaystyle 3072\)

\(\displaystyle 9216\)

\(\displaystyle 1024\)

\(\displaystyle 96\)

\(\displaystyle 27648\)

Correct answer:

\(\displaystyle 3072\)

Explanation:

Begin by writing the equations for a cube's dimensions. Namely its volume in terms of the length of its sides:

\(\displaystyle V=s^3\)

The rates of change of the volume can be found by taking the derivative of each side of the equation with respect to time:

\(\displaystyle \frac{dV}{dt}=3s^2\frac{ds}{dt}\)

Now, knowing the length of the sides, simply divide to find the ratio between the rate of change of the volume and sides:

\(\displaystyle 3s^2\frac{ds}{dt}=(\phi)\frac{ds}{dt}\)

\(\displaystyle \phi=3s^2\)

\(\displaystyle \phi =3(32)^2=3072\)

Example Question #663 : How To Find Rate Of Change

A cube is growing in size. What is the ratio of the rate of growth of the cube's volume to the rate of growth of its sides when its sides have length 95?

Possible Answers:

\(\displaystyle 285\)

\(\displaystyle 855\)

\(\displaystyle 27075\)

\(\displaystyle 9025\)

\(\displaystyle 81225\)

Correct answer:

\(\displaystyle 27075\)

Explanation:

Begin by writing the equations for a cube's dimensions. Namely its volume in terms of the length of its sides:

\(\displaystyle V=s^3\)

The rates of change of the volume can be found by taking the derivative of each side of the equation with respect to time:

\(\displaystyle \frac{dV}{dt}=3s^2\frac{ds}{dt}\)

Now, knowing the length of the sides, simply divide to find the ratio between the rate of change of the volume and sides:

\(\displaystyle 3s^2\frac{ds}{dt}=(\phi)\frac{ds}{dt}\)

\(\displaystyle \phi=3s^2\)

\(\displaystyle \phi =3(95)^2=27075\)

Example Question #664 : How To Find Rate Of Change

A cube is diminishing in size. What is the ratio of the rate of loss of the cube's volume to the rate of loss of its sides when its sides have length \(\displaystyle \frac{14}{15}\)?

Possible Answers:

\(\displaystyle \frac{14}{225}\)

\(\displaystyle \frac{196}{225}\)

\(\displaystyle \frac{14}{75}\)

\(\displaystyle \frac{196}{25}\)

\(\displaystyle \frac{196}{75}\)

Correct answer:

\(\displaystyle \frac{196}{75}\)

Explanation:

Begin by writing the equations for a cube's dimensions. Namely its volume in terms of the length of its sides:

\(\displaystyle V=s^3\)

The rates of change of the volume can be found by taking the derivative of each side of the equation with respect to time:

\(\displaystyle \frac{dV}{dt}=3s^2\frac{ds}{dt}\)

Now, knowing the length of the sides, simply divide to find the ratio between the rate of change of the volume and sides:

\(\displaystyle 3s^2\frac{ds}{dt}=(\phi)\frac{ds}{dt}\)

\(\displaystyle \phi=3s^2\)

\(\displaystyle \phi =3(\frac{14}{15})^2=\frac{196}{75}\)

Example Question #665 : How To Find Rate Of Change

A cube is diminishing in size. What is the ratio of the rate of loss of the cube's volume to the rate of loss of its sides when its sides have length \(\displaystyle \frac{13}{9}\)?

Possible Answers:

\(\displaystyle \frac{169}{9}\)

\(\displaystyle \frac{169}{27}\)

\(\displaystyle \frac{13}{81}\)

\(\displaystyle \frac{169}{81}\)

\(\displaystyle \frac{13}{27}\)

Correct answer:

\(\displaystyle \frac{169}{27}\)

Explanation:

Begin by writing the equations for a cube's dimensions. Namely its volume in terms of the length of its sides:

\(\displaystyle V=s^3\)

The rates of change of the volume can be found by taking the derivative of each side of the equation with respect to time:

\(\displaystyle \frac{dV}{dt}=3s^2\frac{ds}{dt}\)

Now, knowing the length of the sides, simply divide to find the ratio between the rate of change of the volume and sides:

\(\displaystyle 3s^2\frac{ds}{dt}=(\phi)\frac{ds}{dt}\)

\(\displaystyle \phi=3s^2\)

\(\displaystyle \phi =3(\frac{13}{9})^2=\frac{169}{27}\)

Example Question #666 : How To Find Rate Of Change

A cube is diminishing in size. What is the ratio of the rate of loss of the cube's volume to the rate of loss of its sides when its sides have length \(\displaystyle \frac{11}{4}\)?

Possible Answers:

\(\displaystyle \frac{121}{8}\)

\(\displaystyle \frac{363}{16}\)

\(\displaystyle \frac{121}{4}\)

\(\displaystyle \frac{121}{16}\)

\(\displaystyle \frac{363}{4}\)

Correct answer:

\(\displaystyle \frac{363}{16}\)

Explanation:

Begin by writing the equations for a cube's dimensions. Namely its volume in terms of the length of its sides:

\(\displaystyle V=s^3\)

The rates of change of the volume can be found by taking the derivative of each side of the equation with respect to time:

\(\displaystyle \frac{dV}{dt}=3s^2\frac{ds}{dt}\)

Now, knowing the length of the sides, simply divide to find the ratio between the rate of change of the volume and sides:

\(\displaystyle 3s^2\frac{ds}{dt}=(\phi)\frac{ds}{dt}\)

\(\displaystyle \phi=3s^2\)

\(\displaystyle \phi =3(\frac{11}{4})^2=\frac{363}{16}\)

Example Question #667 : How To Find Rate Of Change

A cube is growing in size. What is the ratio of the rate of growth of the cube's surface area to the rate of growth of its diagonal when its sides have length \(\displaystyle 11\sqrt{17}\)?

Possible Answers:

\(\displaystyle 132\sqrt{3}\)

\(\displaystyle 17\sqrt{51}\)

\(\displaystyle 44\sqrt{51}\)

\(\displaystyle 33\sqrt{51}\)

\(\displaystyle 132\sqrt{17}\)

Correct answer:

\(\displaystyle 44\sqrt{51}\)

Explanation:

Begin by writing the equations for a cube's dimensions. Namely its surface area and diagonal in terms of the length of its sides:

\(\displaystyle A=6s^2\)

\(\displaystyle d=s\sqrt{3}\)

The rates of change of these can be found by taking the derivative of each side of the equations with respect to time:

\(\displaystyle \frac{dA}{dt}=12s\frac{ds}{dt}\)

\(\displaystyle \frac{dd}{dt}=\sqrt{3}\frac{ds}{dt}\)

Now, knowing the length of the sides, simply divide to find the ratio between the rate of change of the surface area and diagonal:

\(\displaystyle 12s\frac{ds}{dt}=(\phi)\sqrt{3}\frac{ds}{dt}\)

\(\displaystyle \phi=4s\sqrt{3}\)

\(\displaystyle \phi =4(11\sqrt{17})\sqrt{3}=44\sqrt{51}\)

Example Question #668 : How To Find Rate Of Change

A cube is growing in size. What is the ratio of the rate of growth of the cube's surface area to the rate of growth of its diagonal when its sides have length \(\displaystyle 2\sqrt{10}\)?

Possible Answers:

\(\displaystyle 12\sqrt{15}\)

\(\displaystyle 4\sqrt{15}\)

\(\displaystyle 80\sqrt{3}\)

\(\displaystyle 8\sqrt{30}\)

\(\displaystyle 16\sqrt{15}\)

Correct answer:

\(\displaystyle 8\sqrt{30}\)

Explanation:

Begin by writing the equations for a cube's dimensions. Namely its surface area and diagonal in terms of the length of its sides:

\(\displaystyle A=6s^2\)

\(\displaystyle d=s\sqrt{3}\)

The rates of change of these can be found by taking the derivative of each side of the equations with respect to time:

\(\displaystyle \frac{dA}{dt}=12s\frac{ds}{dt}\)

\(\displaystyle \frac{dd}{dt}=\sqrt{3}\frac{ds}{dt}\)

Now, knowing the length of the sides, simply divide to find the ratio between the rate of change of the surface area and diagonal:

\(\displaystyle 12s\frac{ds}{dt}=(\phi)\sqrt{3}\frac{ds}{dt}\)

\(\displaystyle \phi=4s\sqrt{3}\)

\(\displaystyle \phi =4(2\sqrt{10})\sqrt{3}=8\sqrt{30}\)

Example Question #669 : How To Find Rate Of Change

A cube is growing in size. What is the ratio of the rate of growth of the cube's surface area to the rate of growth of its diagonal when its sides have length \(\displaystyle 2\sqrt{42}\)?

Possible Answers:

\(\displaystyle 7\sqrt{51}\)

\(\displaystyle 24\sqrt{14}\)

\(\displaystyle 16\sqrt{42}\)

\(\displaystyle 8\sqrt{42}\)

\(\displaystyle 12\sqrt{14}\)

Correct answer:

\(\displaystyle 24\sqrt{14}\)

Explanation:

Begin by writing the equations for a cube's dimensions. Namely its surface area and diagonal in terms of the length of its sides:

\(\displaystyle A=6s^2\)

\(\displaystyle d=s\sqrt{3}\)

The rates of change of these can be found by taking the derivative of each side of the equations with respect to time:

\(\displaystyle \frac{dA}{dt}=12s\frac{ds}{dt}\)

\(\displaystyle \frac{dd}{dt}=\sqrt{3}\frac{ds}{dt}\)

Now, knowing the length of the sides, simply divide to find the ratio between the rate of change of the surface area and diagonal:

\(\displaystyle 12s\frac{ds}{dt}=(\phi)\sqrt{3}\frac{ds}{dt}\)

\(\displaystyle \phi=4s\sqrt{3}\)

\(\displaystyle \phi =4(2\sqrt{42})\sqrt{3}=24\sqrt{14}\)

Example Question #670 : How To Find Rate Of Change

A cube is growing in size. What is the ratio of the rate of growth of the cube's surface area to the rate of growth of its diagonal when its sides have length \(\displaystyle 3\sqrt{39}\)?

Possible Answers:

\(\displaystyle 108\sqrt{13}\)

\(\displaystyle 12\sqrt{13}\)

\(\displaystyle 36\sqrt{39}\)

\(\displaystyle 36\sqrt{13}\)

\(\displaystyle 12\sqrt{39}\)

Correct answer:

\(\displaystyle 36\sqrt{13}\)

Explanation:

Begin by writing the equations for a cube's dimensions. Namely its surface area and diagonal in terms of the length of its sides:

\(\displaystyle A=6s^2\)

\(\displaystyle d=s\sqrt{3}\)

The rates of change of these can be found by taking the derivative of each side of the equations with respect to time:

\(\displaystyle \frac{dA}{dt}=12s\frac{ds}{dt}\)

\(\displaystyle \frac{dd}{dt}=\sqrt{3}\frac{ds}{dt}\)

Now, knowing the length of the sides, simply divide to find the ratio between the rate of change of the surface area and diagonal:

\(\displaystyle 12s\frac{ds}{dt}=(\phi)\sqrt{3}\frac{ds}{dt}\)

\(\displaystyle \phi=4s\sqrt{3}\)

\(\displaystyle \phi =4(3\sqrt{39})\sqrt{3}=36\sqrt{13}\)

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