Calculus AB : Calculus AB

Study concepts, example questions & explanations for Calculus AB

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Example Questions

Example Question #1 : Calculate Position, Velocity, And Acceleration

A particle's position on the -axis is given by the function from .

When does the particle change direction?

Possible Answers:

It doesn't change direction within the given bounds

Correct answer:

It doesn't change direction within the given bounds

Explanation:

To find when the particle changes direction, we need to find the critical values of . This is done by finding the velocity function, setting it equal to , and solving for 

.

Hence .

The solutions to this on the unit circle are , so these are the values of  where the particle would normally change direction. However, our given interval is , which does not contain . Hence the particle does not change direction on the given interval.

Example Question #4 : Calculate Position, Velocity, And Acceleration

A particle moves in space with velocity given by

 

where  are constant parameters. 

Find the acceleration of the particle when .

Possible Answers:

Correct answer:

Explanation:

To find the acceleration of the particle, we must take the first derivative of the velocity function:

The derivative was found using the following rule:

Now, we evaluate the acceleration function at the given point:

Example Question #21 : Contextual Applications Of Derivatives

Find the velocity function from an acceleration function given by

 

and the condition 

Possible Answers:

Correct answer:

Explanation:

Acceleration is the rate of change of velocity, so we must integrate the acceleration function to find the velocity function:

The integration was performed using the following rules:

To find the integration constant C, we must use the initial condition given:

Our final answer is

Example Question #321 : Calculus Ab

The velocity of a particle is given by v(t). Find the function which models the particle's acceleration.

Possible Answers:

Correct answer:

Explanation:

The velocity of a particle is given by v(t). Find the function which models the particle's acceleration.

To find the acceleration from a velocity function, simply take the derivative.

In this case, we are given v(t), and we need to find v'(t) because v'(t)=a(t).

To find v'(t), we need to use the power rule. 

For each term, simply multiply by the exponent, and then subtract one from the exponent. Constant terms will drop out, linear terms will become constants, and so on.

So, our answer is:

Example Question #11 : Calculate Position, Velocity, And Acceleration

The velocity of a particle is given by . Find the particle's acceleration when .

Possible Answers:

Correct answer:

Explanation:

The velocity of a particle is given by . Find the particle's acceleration when .

To find the acceleration from a velocity function, simply take the derivative.

In this case, we are given , and we need to find  because .

To find , we need to use the power rule. 

For each term, simply multiply by the exponent, and then subtract one from the exponent. Constant terms will drop out, linear terms will become constants, and so on.

So, our acceleration function is:

Now, plug in  for  and solve.

So, our answer is .

Example Question #1 : Calculate Rates Of Change And Related Rates

A right triangle has sides of length  and  which are both increasing in length over time such that: 

a) Find the rate at which the angle  opposite  is changing with respect to time.

Possible Answers:

Correct answer:

Explanation:

A right triangle has sides of lenght  and  which are both increasing in length over time such that: 

Find the rate at which the angle  opposite  is changing with respect to time.

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a) First, we need to write an expression for the angle  as a function of . Because the angle is opposite the side  we know that the tangent is simply . Take the inverse of the tangent: 

Now we need to differentiate with respect to 

Recall the general derivative for the inverse tangent function is:

 

Applying this to our function for , and remembering to use the chain rule, we obtain: 

Example Question #2 : Calculate Rates Of Change And Related Rates

Soap is sometimes used to determine the location of leaks in industrial pipes. A perfectly spherical soap bubble is growing at a rate of . What is the rate of change of the surface area of the bubble when the radius of the bubble is ?

Possible Answers:

Correct answer:

Explanation:

To determine the rate of change of the surface area of the spherical bubble, we must relate it to something we do know the rate of change of - the volume. 

The volume of a sphere is given by the following:

The rate of change of the volume is given by the derivative with respect to time:

The derivative was found using the following rules:

We must now solve for the rate of change of the radius at the specified radius, so that we can later solve for the rate of change of surface area:

Next, we must find the surface area and rate of change of the surface area of the sphere the same way as above:

Plugging in the known rate of change of the surface area at the specified radius, and this radius into the rate of surface area change function, we get

Example Question #1 : Calculate Rates Of Change And Related Rates

A pizzeria chef is flattening a circular piece of dough. The surface area of the dough (we are only considering the top of the dough) is increasing at a rate of 0.5 inches/sec. How quickly is the diameter of the pizza changing when the radius of the pizza measures 4 inches?

Possible Answers:

 inches/sec

 inches/sec

 inches/sec

 inches/sec

 inches/sec

Correct answer:

 inches/sec

Explanation:

To find the rate of change of the diameter, we must relate the diameter to something we do know the rate of change of: the surface area.

The surface area of the top side of the pizza dough is given by

The rate of change, then, is found by taking the derivative of the function with respect to time:

Solving for the rate of change of the radius at the given radius, we get

 inches/sec

Now, we relate the diameter to the radius of the pizza dough:

Taking the derivative of both sides with respect to time, we get

Plugging in the known rate of change of the radius at the given radius, we get

 inches/sec

We could have found this directly by writing our surface area formula in terms of diameter, however the process we used is more applicable to problems in which the related rate of change is of something not as easy to manipulate.

Example Question #2 : Calculate Rates Of Change And Related Rates

A spherical balloon is increasing in volume at a constant rate of . At a radius of 3 cm, what is the rate of change of the circumference of the balloon?

Possible Answers:

Correct answer:

Explanation:

To determine the rate of change of the circumference at a given radius, we must relate the circumference rate of change to the rate of change we know - that of the volume.

Starting with the equation for the volume of the spherical balloon,

we take the derivative of the function with respect to time, giving us the rate of change of the volume:

The derivative was found using the following rules:

The chain rule was used when taking the derivative of the radius with respect to time, because we know that it is a function of time.

Solving for  using our known  at the given radius, we get

Now, we use this rate of change and apply it to the rate of change of the circumference, which we get by taking the derivative of the circumference with respect to time:

Solving for the rate of change of the circumference by plugging in the known rate of change of the radius, we get

Example Question #3 : Calculate Rates Of Change And Related Rates

Determine the rate of change of the angle opposite the base of a right triangle -whose length is increasing at a rate of 1 inch per minute, and whose height is a constant 2 inches - when the area of the triangle is 2 square inches.

Possible Answers:

  radians per minute

 radians per minute

 radians per minute

 radians per minute

Correct answer:

 radians per minute

Explanation:

To determine the rate of the change of the angle opposite to the base of the given right triangle, we must relate it to the rate of change of the base of the triangle when the triangle is a certain area. 

First, we must determine the length of the base of the right triangle at the given area:

Now, we must find something that relates the angle opposite of the base to the length of the base and height - the tangent of the angle:

To find the rate of change of the angle, we take the derivative of both sides with respect to time, keeping in mind that the base of the triangle is dependent on time, while the height is constant:

We know the rate of change of the base, and we can find the angle from the sides of the triangle:

Plugging this and the other known information in and solving for the rate of change of the angle adjacent to the base, we get

 radians per minute

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