Help with periods and oscilation *and* wavelengths

Click For Summary

Homework Help Overview

The discussion revolves around the properties of water waves in a shallow dish, specifically focusing on their wavelength and oscillation frequency. The original poster seeks to determine the speed and period of these waves based on given values.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the relationship between wavelength, frequency, and speed, referencing relevant equations. There are questions about unit conversions and the meaning of oscillations in terms of frequency. Some participants express confusion about how to manipulate equations to find the period from the frequency.

Discussion Status

Participants are actively engaging with the problem, asking clarifying questions and exploring algebraic manipulations. Some guidance has been provided regarding unit conversions and the interpretation of frequency, but there is still uncertainty about the calculations and the underlying concepts.

Contextual Notes

There is a noted emphasis on converting units to MKS (meters, kilograms, seconds) for consistency in calculations. Participants are also grappling with the definitions and implications of frequency and period in the context of wave motion.

Sonny18n
Messages
60
Reaction score
0

Homework Statement



Water waves in a shallow dish are 6.0 cm 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?

Homework Equations


frequency = 1/period
Speed = wavelength x frequency

The Attempt at a Solution


Guessing 6.0 cm is thr wavelength but that wouldn't help much since I'm looking for the period and I don't even know what oscillations are.
 
Last edited by a moderator:
Physics news on Phys.org
Sonny18n said:

Homework Statement



Water waves in a shallow dish are 6.0 cm 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?

Homework Equations


frequency = 1/period
Speed = wavelength x frequency

The Attempt at a Solution


Guessing 6.0 cm is thr wavelength but that wouldn't help much since I'm looking for the period and I don't even know what oscillations are.

You show a relevant equation for calculating the speed from the wavelength and frequency. You are given both in the problem statement.

Be sure to be careful with your units. You should convert everything into MKS units for this problem.
 
berkeman said:
You show a relevant equation for calculating the speed from the wavelength and frequency. You are given both in the problem statement.

Be sure to be careful with your units. You should convert everything into MKS units for this problem.
Do I convert the 6.0 cm to meters because its wavelength? I don't understand what 4.8 oscillations a second translates into frequency or speed
 
Sonny18n said:
Do I convert the 6.0 cm to meters because its wavelength? I don't understand what 4.8 oscillations a second translates into frequency or speed

Yes, convert 6cm into meters, so you can calculate the speed.

When they say 4.8 oscillations per second, that is the same as saying that the frequency is 4.8Hz. Hz is "Hertz", and is equal to one oscillation per second. You write the units of Hz as 1/s. Try to always carry along the units for each quantity in your calculations, and cancel them when you have the same units in the numerator and denominator of a fraction. That helps you to use units to check your calculations.
 
berkeman said:
Yes, convert 6cm into meters, so you can calculate the speed.

When they say 4.8 oscillations per second, that is the same as saying that the frequency is 4.8Hz. Hz is "Hertz", and is equal to one oscillation per second. You write the units of Hz as 1/s. Try to always carry along the units for each quantity in your calculations, and cancel them when you have the same units in the numerator and denominator of a fraction. That helps you to use units to check your calculations.
So it would be 0.288m/s?
And for b) is the answer 4.8s?
 
Sonny18n said:
So it would be 0.288m/s?
And for b) is the answer 4.8s?

Yes on the first one -- v = 0.06m * 4.8Hz = 0.288m/s.

On the 2nd one, they have given you the frequency as 4.8Hz. Use your other equation to figure out the period that is associated with that frequency...
 
berkeman said:
Yes on the first one -- v = 0.06m * 4.8Hz = 0.288m/s.

On the 2nd one, they have given you the frequency as 4.8Hz. Use your other equation to figure out the period that is associated with that frequency...
But I'm looking for period and I only have frequency and the number "1".
 
Sonny18n said:
But I'm looking for period and I only have frequency and the number "1".

Sonny18n said:
frequency = 1/period

What does that relevant equation mean? What does it mean to take 1/anything? What is 1/2? What is 1/10? :smile:
 
berkeman said:
What does that relevant equation mean? What does it mean to take 1/anything? What is 1/2? What is 1/10? :smile:
Are you asking me to divide 1 by so and so? I don't know what that so and so is.
 
  • #10
Sonny18n said:
Are you asking me to divide 1 by so and so? I don't know what that so and so is.

If frequency = 1/period, and you have the frequency and want to find the period, what simple algebraic manipulation do you use to get the equation for period in terms of frequency?
 
  • #11
berkeman said:
If frequency = 1/period, and you have the frequency and want to find the period, what simple algebraic manipulation do you use to get the equation for period in terms of frequency?
Okay just realized where you were going with the last hint. It's probably incredible simple but I draw a blank as to what 1 can be divided to get a number as big as 4.8
 
  • #12
Sonny18n said:
Okay just realized where you were going with the last hint. It's probably incredible simple but I draw a blank as to what 1 can be divided to get a number as big as 4.8

Just to review some algebra...

If y = 1/x, and you are given y, how do you solve for x?
 
  • #13
berkeman said:
Just to review some algebra...

If y = 1/x, and you are given y, how do you solve for x?
I would've thought it was to multily y and 1 to get 4.8 but 1 divided by 4.8 clearly isn't 4.8
 
  • #14
Sonny18n said:
I would've thought it was to multily y and 1 to get 4.8 but 1 divided by 4.8 clearly isn't 4.8

Stick with my more general algebra example for a bit. In algebra, we manipulate equations to change there form in order to get to our answer. As long as we do the same thing to both sides of an equation, the equality still holds. We can add the same number to both sides, for example. Or we can multiply both sides by the same constant, or by the same variable.

What can you do to this equation: y = 1/x

To get it into the forum of x = f(y), where (y) is some function of y that you got to by a couple manipulations of the original equation?
 
  • #15
berkeman said:
Stick with my more general algebra example for a bit. In algebra, we manipulate equations to change there form in order to get to our answer. As long as we do the same thing to both sides of an equation, the equality still holds. We can add the same number to both sides, for example. Or we can multiply both sides by the same constant, or by the same variable.

What can you do to this equation: y = 1/x

To get it into the forum of x = f(y), where (y) is some function of y that you got to by a couple manipulations of the original equation?
Okay so I was messing with the numbers and divided 1 by 4.8. Then I got 0.2083 to which I divided it to 1 and got 4.8
 
  • #16
Sonny18n said:
Okay so I was messing with the numbers and divided 1 by 4.8. Then I got 0.2083 to which I divided it to 1 and got 4.8

Please answer my question in Post #14. Just blindly manipulating equations is pointless. Please use real algebra, and write out each step...
 
  • #17
berkeman said:
Please answer my question in Post #14. Just blindly manipulating equations is pointless. Please use real algebra, and write out each step...
Well it works with 2 as well. 1/2 is .5 and .5 goes into one 2 times.
 

Similar threads

Spring set makes up a traveling wave
  • · Replies 16 ·
Replies
16
Views
4K
Waves - General question about Damping and how it affects a propagating wave
  • · Replies 1 ·
Replies
1
Views
3K
Amplitude relation with periodic time
  • · Replies 3 ·
Replies
3
Views
2K
Find wavelength, frequency and speed of a wave,
  • · Replies 5 ·
Replies
5
Views
6K
How Many Oscillations Has This Wave Completed?
  • · Replies 18 ·
Replies
18
Views
2K
Water waves travelling from deep to shallow water
  • · Replies 4 ·
Replies
4
Views
2K
Apparent wavelength in Doppler's effect
  • · Replies 7 ·
Replies
7
Views
2K
Wave equation, wavelenght not given
  • · Replies 6 ·
Replies
6
Views
2K
Wavelength Calculation in a Ripple Tank with Varying Speeds
  • · Replies 1 ·
Replies
1
Views
1K
How to find wavelength of wave?
  • · Replies 4 ·
Replies
4
Views
2K