5. Given the equation y = (1/4) cos[(2pi/3)*theta]: 5a. For the general equation y = a cos(bx), the period is given by 2pi/b. In this equation, b = 2pi/3, so this means that 2pi/b = 2pi/(2pi/3) = 3. Therefore, the period of this equation is 3, and the cosine wave repeats itself every 3 x-units. 5b. For the general equation y = a cos(bx), the amplitude is given by a. Therefore the amplitude is a = 1/4, and this means that the cosine wave's range is from -1/4 to 1/4 for all values of x. 5c. The equation of the midline is y = 0. This represents the average value over the wave. This is determined by adding the highest and lowest values of the range and taking the average, in this case, 1/4 + (-1/4) = 0, and 0 / 2 = 0. Another way to do this is using the general equation y = a cos(bx) + c, where the midline's equation is y = c. In this case, there is no value of c in the given, implying that c = 0, and the midline is y = 0.
6. Let the horizontal distance be x. Then tan42 = h/x, and h = x tan42. Then using the Pythagorean theorem: 3280^2 = h^2 + x^2 3280^2 = x^2 (tan42)^2 + x^2 3280^2 = x^2 [(tan42)^2 + 1] x = 2437.52 Therefore, h = x tan42 = 2,194.75 ft.
Because we required two (2) pounds to stretch the spring eight (8) inches, we need double the force to stretch it sixteen (16) inches. Sixteen is just double the original amount, meaning we need four (4) pounds to stretch the spring sixteen inches.
