# I need alot of help

1. Jun 17, 2004

### BRITTANI

I have alot of questions to be answered, but i want to understand how i am doing it so if anyone can help me one on one today, i'd appreciate it much. here are a few problems:

(1)the sears building in chicago sways back and forth with a frequency of about 10.0 Hz. what is its period?
(2)an ocean wave has a length of 10.0m. a wave passes a fixed location every 2.0 s. what is the speed of the wave?
(3)water waves in a shallow dish are 6.0cm long. at one point, the water oscillates up and down at a rate of 4.8 oscillations per second.
a.what is the speed of the water waves?
b.what is the period of the water waves?
(4)water waves in a lake travel 4.4m in 1.8s. the period or oscillation is 1.2s.
a. what is the speed of the water waves?
b. what are their wavelength?
(5)the frequency of yellow light is 5.0 * 10 ^14 Hz. Find its wavelength.
(6)the wave speed in a guitar string is 265 m/s. the length of the string is 63 cm. you pluck the center of the string by pulling it up and letting go. pulses move in both directions and are reflected off the ends of the string.
a.how long does it take for the pulse to move to the string end and return to the center?
b.when the pulses return, is the string above or below its resting location?
c.if you plucked the string 15 cm from from one end of the string, where would the two pulses meet?

i have more questions but theres a start

2. Jun 17, 2004

Hello BRITTANI,
Welcome to PF !

You stated you wanted know how you are doing with this, but it would be impossible to comment on this because you never demonstrated you had actually done anything.

Anyway, I only read the first problem;

(1)the sears building in chicago sways back and forth with a frequency of about 10.0 Hz. what is its period?

I'd be willing to venture a guess if you look up the word 'period' in the Glossary or Index you could find out what you needed to know. There is a very simple mathematical relationship between Frequency and Period. Do you have any idea what it might be?

Good luck

3. Jun 18, 2004

### Nec

Hello BRITTANI,
Welcome to PF !

You stated you wanted know how you are doing with this, but it would be impossible to comment on this because you never demonstrated you had actually done anything.

Anyway, I only read the second problem;

(2)an ocean wave has a length of 10.0m. a wave passes a fixed location every 2.0 s. what is the speed of the wave?

I'd be willing to venture a guess if you look up the formula representing the relationship of lamda, time, and velocity you could come to know...That is a very simple mathematical relationship among them...

Do you have any idea what it might be?

Good luck

4. Jun 18, 2004

### arildno

A good start would be to write a post in which you state which formulae you think you'll need, and then comment on specific questions where you are uncertain about how to proceed (and preferably, why)

5. Jun 18, 2004

### HallsofIvy

Staff Emeritus
By the way, as is often the case in mathematics (and other things!) a lot of these problems depend on knowing the precise definitions of the words in the problem.