Homework Help: Question on oscillations spring balance and fish

1. Jan 30, 2010

squintyeyes

The scale of a spring balance reading from zero to 180 N is 7.00 cm long. A fish suspended from the balance is observed to oscillate vertically at 2.50 Hz. What is the mass of the fish? Neglect the mass of the spring.
________ kg

Attempt
k =(180-0)/(7-0) = 25.714 N/m

frequency = (m/k)^(1/2)
2.5 = (m/25.714)^(1/2)
6.25 = m/25.714
m = 160.714 kg

I am pretty certain this is wrong.

2. Jan 30, 2010

cepheid

Staff Emeritus
I think there are two problems. The first is that the equation is actually:

$$\omega = \sqrt{\frac{k}{m}}$$ ​

and you have the reciprocal of that. The second problem is that omega is not quite the same thing as the frequency of oscillation.

3. Jan 31, 2010

squintyeyes

yeah but what is the spring constant, K. I sort of need that to solve the problem.

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The text passage contains a physics problem related to the oscillation of a fish on a spring balance, including an attempt at a solution and a response from a staff member pointing out potential issues with the approach.
single_question_with_answer

the passage includes a single mathematical question about finding the mass of a fish based on the oscillation frequency and the spring constant, and an attempt at an answer is provided.
Given a text passage, determine:
    1. If it contains a mathematical question (including word problems or calculations)
    2. If an answer to that mathematical question is provided in the text

First, describe the content structure you found in 1-2 sentences.

Then provide your analysis in the following format:
TYPE: <one of the following values>
- NO_QUESTION
- SINGLE_QUESTION
- SINGLE_QUESTION_WITH_ANSWER
- MULTIPLE_QUESTIONS
- MULTIPLE_QUESTIONS_WITH_ANSWERS
system
Homework Help: Question on oscillations spring balance and fish

1. Jan 30, 2010

squintyeyes

The scale of a spring balance reading from zero to 180 N is 7.00 cm long. A fish suspended from the balance is observed to oscillate vertically at 2.50 Hz. What is the mass of the fish? Neglect the mass of the spring.
________ kg

Attempt
k =(180-0)/(7-0) = 25.714 N/m

frequency = (m/k)^(1/2)
2.5 = (m/25.714)^(1/2)
6.25 = m/25.714
m = 160.714 kg

I am pretty certain this is wrong.

2. Jan 30, 2010

cepheid

Staff Emeritus
I think there are two problems. The first is that the equation is actually:

$$\omega = \sqrt{\frac{k}{m}}$$ ​

and you have the reciprocal of that. The second problem is that omega is not quite the same thing as the frequency of oscillation.

3. Jan 31, 2010

squintyeyes

yeah but what is the spring constant, K. I sort of need that to solve the problem.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook
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The text passage contains a physics problem related to the oscillation of a fish on a spring balance, including an attempt at a solution and a response from a staff member pointing out potential issues with the approach.

TYPE: SINGLE_QUESTION_WITH_ANSWER

The passage includes a single mathematical question about finding the mass of a fish based on the oscillation frequency and the spring constant, and an attempt at an answer is provided.