Question

The equation h=7sin(pi/21t)+28 can be used to model the height, h, in feet of the end of one blade of a windmill turning on an axis above the ground as a function of time, t, in seconds. How long is the blade? Assume that the blade is pointing to the right, parallel to the ground, at t = 0, and that the windmill turns counterclockwise at a constant rate. 7 feet 14 feet 21 feet 28 feet

Answer 1

7

Explanation:

7 feet

Answer 2

7 feet is the length of the blade of the windmill.

Explanation:

We have the equation

h = 7 sin(pi/21t) + 28 ------ eq1

At time 't' = 0, the end of the blade is pointing to the right parallel to the ground meaning it is at the same height as the other end. (Ф = 0°)

So, by calculating the maximum height of this end at Ф = 90°. we can calculate the length of the blade.

Now, we know that a general model equation of a circular simple harmonic motion is represented as : y = A sinωt + k ----- eq2

Where A is the amplitude that is, maximum displacement from mean to maximum position.

ω is the angular frequency.

Comparing eq1 and eq2:

A = 7

so the difference in blades end height at Ф = 0° and Ф = 90° is 7 feet.

Hence, the length of the blade is 7 feet.