Question

The paddle wheel of a boat measures 16 feet in diameter and is revolving at a rate of 20 rpm. The maximum depth of the paddle wheel under water is 1 foot. Suppose a point is located at the lowest point of the wheel at t=0.

1. Write a cosine function with phase shift 0 for height above water of the initial point after t seconds.
a. h=8cos((2π)/2 t)+7
b. h=-8cos3t+7
c. h=-8cos((2π)/3 t)+7
d. h=8cos3t+7

I think this is C?

2. use your function to find the height of the initial point after 5.5 seconds.
a. 7.5 ft
b. 11 ft
c. 10.4 ft
d. 6.5 ft

Answer 1

The period is clearly 60/20 seconds, or 3 seconds.

the cosine function should be of the form
cos(2PI/period* t)

C. is correct.

Answer 2

so would 2. be C as well?