The hour hand of the large clock on the wall in Union Station measures 24 inches in length. At noon, the tip of the hour hand is 30 inches from the ceiling. At 3 PM, the tip is 54 inches from the ceiling, and at 6 PM, 78 inches. At 9 PM, it is again 54 inches from the ceiling, and at midnight, the tip of the hour hand returns to its original position 30 inches from the ceiling. Let
equal the distance from the tip of the hour hand to the ceiling
hours after noon. Find the equation that models the motion of the clock and sketch the graph.
Begin by making a table of values as shown in
[link] .
Points to plot
Noon
30 in
3 PM
54 in
6 PM
78 in
9 PM
54 in
Midnight
30 in
To model an equation, we first need to find the amplitude.
The clock’s cycle repeats every 12 hours. Thus,
The vertical shift is
There is no horizontal shift, so
Since the function begins with the minimum value of
when
(as opposed to the maximum value), we will use the cosine function with the negative value for
In the form
the equation is
The height of the tide in a small beach town is measured along a seawall. Water levels oscillate between 7 feet at low tide and 15 feet at high tide. On a particular day, low tide occurred at 6 AM and high tide occurred at noon. Approximately every 12 hours, the cycle repeats. Find an equation to model the water levels.
As the water level varies from 7 ft to 15 ft, we can calculate the amplitude as
The cycle repeats every 12 hours; therefore,
is
There is a vertical translation of
Since the value of the function is at a maximum at
we will use the cosine function, with the positive value for
The daily temperature in the month of March in a certain city varies from a low of
to a high of
Find a sinusoidal function to model daily temperature and sketch the graph. Approximate the time when the temperature reaches the freezing point
Let
correspond to noon.
The temperature reaches freezing at noon and at midnight.
The average person’s blood pressure is modeled by the function
where
represents the blood pressure at time
measured in minutes. Interpret the function in terms of period and frequency. Sketch the graph and find the blood pressure reading.
The period is given by
In a blood pressure function, frequency represents the number of heart beats per minute. Frequency is the reciprocal of period and is given by
Harmonic motion is a form of periodic motion, but there are factors to consider that differentiate the two types. While general
periodic motion applications cycle through their periods with no outside interference,
harmonic motion requires a restoring force. Examples of harmonic motion include springs, gravitational force, and magnetic force.
Questions & Answers
for the "hiking" mix, there are 1,000 pieces in the mix, containing 390.8 g of fat, and 165 g of protein. if there is the same amount of almonds as cashews, how many of each item is in the trail mix?
an object is traveling around a circle with a radius of 13 meters .if in 20 seconds a central angle of 1/7 Radian is swept out what are the linear and angular speed of the object
like this: (2)/(2-x)
the aim is to see what will not be compatible with this rational expression. If x= 0 then the fraction is undefined since we cannot divide by zero. Therefore, the domain consist of all real numbers except 2.
functions can be understood without a lot of difficulty.
Observe the following:
f(2) 2x - x
2(2)-2= 2
now observe this:
(2,f(2)) ( 2, -2)
2(-x)+2 = -2
-4+2=-2
a colony of bacteria is growing exponentially doubling in size every 100 minutes. how much minutes will it take for the colony of bacteria to triple in size
100•3=300
300=50•2^x
6=2^x
x=log_2(6)
=2.5849625
so, 300=50•2^2.5849625
and, so,
the # of bacteria will double every (100•2.5849625) =
258.49625 minutes
Thomas
158.5
This number can be developed by using algebra and logarithms.
Begin by moving log(2) to the right hand side of the equation like this:
t/100 log(2)= log(3)
step 1: divide each side by log(2)
t/100=1.58496250072
step 2: multiply each side by 100 to isolate t.
t=158.49
Dan
what is the importance knowing the graph of circular functions?
yeah, it does. why do we attempt to gain all of them one side or the other?
Melissa
how to find x:
12x = 144
notice how 12 is being multiplied by x. Therefore division is needed to isolate x
and whatever we do to one side of the equation we must do to the other.
That develops this:
x= 144/12
divide 144 by 12 to get x.
addition:
12+x= 14
subtract 12 by each side. x =2
The domain of a function is the set of all input on which the function is defined. For example all real numbers are the Domain of any Polynomial function.
Spiro
Spiro; thanks for putting it out there like that, 😁
Melissa
foci (–7,–17) and (–7,17), the absolute value of the differenceof the distances of any point from the foci is 24.
