1.) the radio wave from a station broadcasting at 1.3×10^6 hz has a wavelength of 230 m. what is the wave's speed? 2.) a wave has a frequency of 575 hz. what is its period? 3.) a humming bird feeder is tied by a rope to a tree branch. you notice that in a gentle breeze, the feeder moves back and forth 15 times in 1 minute. how long is the rope?

a. 600 N/m

Hooke's law states that:

F = kx

where

F is the force applied

k is the spring constant

x is the stretching/compression of the spring relative to the equilibrium position

In this problem we have

F = 60 N

x = 0.1 m

So the spring constant is

b. 75 J

The work required to stretch a spring is equal to the elastic potential energy stored in the spring:

where

k is the spring constant

x is the stretching/compression of the spring

Here we have

k = 600 N/m

x = 0.5 m

So the work done is

c. 108 J

We can use the same formula used in the previous part:

where here we have

k = 600 N/m

x = 0.6 m

So the work done is

d. 9 J

In this case, the additional work required is the difference between the elastic potential energy in the two situations

where

k = 600 N/m

is the initial stretching

is the final stretching

Solving the equation,