All Calculus 1 Resources
Example Questions
Example Question #52 : How To Find Rate Of Change
The length of a rectangle is 50 feet and the width is 40 feet at a certain moment. If the length is increasing at 2 feet per second and the width is decreasing at 0.5 feet per second, how fast is the area of the rectangle changing at the same moment?
None of the above.
In order to solve this problem, we must first know that the area for a rectangle is . In order to find the rate at which the area of the rectangle changes with respect to time, we simply take the derivative of the formula for the area of a rectangle with respect to time. In order to do so, we must apply the product rule,
.
Applying the product rule, the derivative becomes
.
Because we know that
, we simply plug those into the equation to solve for
.
Example Question #53 : How To Find Rate Of Change
A circle's circumference is increasing at a rate of 0.6 feet per second. If the diameter of the circle is 80 feet at a moment, how fast is the area of the circle increasing at the same moment?
None of the above.
In order to solve this problem, we must know that the circumfrence of a circle is equivalent to .
Therefore by taking the derivative with respect to time, we obtain
.
Given that we know that
, we can solve for
.
In order to solve for how fast the area of the circle changes, we must know that the area of a circle is defined as .
Taking the derivative with respect to time, we obtain
.
We know that , so by plugging in all the variables, we can solve for
.
.
Example Question #51 : How To Find Rate Of Change
Find the rate of change of the function .
The rate of change of a function is its derivative.
Recall the following rules of differentiation to help solve this problem.
Power Rule:
Differentiation rule for tangent:
Therefore, the rate of change of , by the power rule and the differentiation rule for tangent, is
.
Example Question #51 : How To Find Rate Of Change
The sides of a square shrink at a rate of . What is the rate of growth of the square if its sides have lengths of
?
The area of a square is given by the formula:
The rate of growth of the area can be related to the rate of growth of sides by differentiating each side with respect to time:
Therefore, the rate of growth of the square is:
Example Question #141 : Rate
The area of a circle is increasing at a rate of . If the area of the circle is
, what is the rate of increase of the radius?
The area of circle in terms of its radius is given as:
This can be rewritten to find the radius:
In this problem, the radius can be found to be:
Now, relate rates of change by deriving each side of the area equation with respect to time:
Solve then for :
Example Question #61 : How To Find Rate Of Change
A triangle is growing taller at a rate of . If it has a base of
and height of
, how fast is the area of the triangle changing?
The area of a triangle in terms of its base and height is given by the formula:
To find how the rates of change of each term relate, derive each side of the equation with respect to time:
The base isn't widening, so
Therefore:
Example Question #2972 : Calculus
A rectangle is inexplicably changing in shape. Its length is growing at a rate of and its width is shrinking at a rate of
. If the length is
and its width is
, what is the rate of change of the area?
The area of a rectangle is given in terms of its length and width as:
.
The rates of change of each parameter with respect to time can be found by deriving each side of the equation with respect to time:
Therefore, with our known values, it's possible to find the inexplicable rate of change of the rectangle. Remember that the width is shrinking, so its rate should be treated as negative:
Example Question #61 : How To Find Rate Of Change
The sides of a square are shrinking at an increasing rate. If the rate of rate increase is , the rate of increase is
and the sides of a length of
, what is the rate at which the rate of growth of the area of the square is changing?
Note for this problem, we're looking for a change in a rate, so this is dealing with second time derivatives:
Relating the area of a square to length:
Leads to
Now, it's important to note that the term cannot be ignored in this second derivation; treat it like another variable!
Plugging in the given values, this gives:
Example Question #2973 : Calculus
A child is breathing into a bubble wand to create a soap bubble. Treating the bubble as an expanding sphere, If the sphere has a volume of and is growing at a rate of
, what is the rate of growth of the sphere's radius?
Begin this problem by solving for the radius. The volume of a sphere is given as
Solving for the radius:
Now time rate of change between quantities can be found by deriving each side with respect to time:
Solving for the radius rate of time then gives:
Example Question #2974 : Calculus
A triangle is being stretched in a peculiar way. The base is shrinking at a rate of while the height is increasing at a rate of
. If the height of the triangle is
and the base of the triangle is
, what is the rate of change of the triangle's area?
The area of a triangle is given by the function:
The relationship between the rate of change of each parameter can be found by deriving each side of the equation with respect to time:
Certified Tutor
Certified Tutor
All Calculus 1 Resources
