How Is Tension Calculated in a Plucked Telephone Cord?

[nemzy]

A telephone cord is 4.00 m long and has a mass of 0.300 kg. A transverse wave pulse is produced by plucking one end of the taut cord. The pulse makes three trips down and back along the cord in 0.700 s. What is the tension in the cord?


ok, this problem seems very easy and straightforward but i am getting it wrong..i have absolute no idea why ..i hate physics can't wait till i finish this damn course...

anyways...

t=time
T=tension
u=mass/length
L=total length

t=L*sqrt(u/T)

simple, and just solve for T right? But i am getting it wrong why??

t=.7 sec
u=(.300 kg/4 m)
L= 3*(4 m)

i have all the variables but T and solve for T and get 22.03 N

but the answer is wrong does any 1 know where i went wrong thx

 

[Gokul43201]

A telephone cord is 4.00 m long and has a mass of 0.300 kg. A transverse wave pulse is produced by plucking one end of the taut cord. The pulse makes three trips down and back along the cord in 0.700 s. What is the tension in the cord?


ok, this problem seems very easy and straightforward but i am getting it wrong..i have absolute no idea why ..i hate physics can't wait till i finish this damn course...

anyways...

t=time
T=tension
u=mass/length
L=total length

t=L*sqrt(u/T)

simple, and just solve for T right? But i am getting it wrong why??

t=.7 sec
u=(.300 kg/4 m)
L= 3*(4 m)

i have all the variables but T and solve for T and get 22.03 N

but the answer is wrong does any 1 know where i went wrong thx

Yes. What does 't' represent in your formula ? You said it is the time, but it's the time taken for what ? Where did you find that formula ?

Read this part again, carefully :

The pulse makes three trips down and back along the cord in 0.700 s.

 

[blch0901]

I'm also doing a similar problem.
An ethernet cable is 4.10 m long and has a mass of 0.210 kg. A transverse pulse is produced by plucking one end of the taut cable. The pulse makes four trips down and back along the cable in 0.815 s. What is the tension in the cable?

please help!

 

[kchund]

I am not positive of the answer to your question, but one thing that might help is its actually the square root of T/u tension divided by the linear density not linear density divided by tension

 

[asteriatic]

Dear student,

I understand that you are having difficulty with this problem and are feeling frustrated. Physics can be a challenging subject, but with perseverance and practice, you can master it.

Let's break down the problem and see where you may have gone wrong. The first step is to identify the given information:

- Length of the telephone cord (L): 4.00 m
- Mass of the telephone cord (m): 0.300 kg
- Number of trips made by the pulse (n): 3
- Time taken for 3 trips (t): 0.700 s

Next, let's identify the variables we need to solve for:

- Tension in the cord (T)

Now, let's use the formula for the speed of a wave on a string:

v = √(T/u)

where v is the speed of the wave, T is the tension in the string, and u is the linear density of the string (mass per unit length).

We can rearrange this formula to solve for T:

T = u * v^2

To find the speed of the wave, we need to calculate the wavelength (λ) and the frequency (f).

We know that the wave pulse makes three trips down and back, so the wavelength is 4.00 m * 3 = 12.00 m. The frequency can be calculated by dividing the number of trips (3) by the time taken (0.700 s), giving us a frequency of 4.29 Hz.

Now, we can calculate the speed of the wave:

v = λ * f = 12.00 m * 4.29 Hz = 51.48 m/s

Finally, we can plug in the values for u and v into our formula for T:

T = (0.300 kg/4.00 m) * (51.48 m/s)^2 = 980.1 N

Therefore, the tension in the cord is 980.1 N.

I hope this explanation helps you understand where you may have gone wrong and how to solve the problem correctly. Remember to always double-check your units and make sure they cancel out to give you the correct unit for the final answer.

Keep practicing and don't give up, you can do it!