Tension of String/ Mass question

In summary, the figure shows two masses hanging from a steel wire, with a wave pulse traveling from point 1 to point 2 in 24.0 ms. Using the equations v = sqrt(Ts/mu) and T = mu*v^2, a tension of 209 N is calculated for a mass of 60 g. However, after converting the mass to kg and using Lami's theorem to find the tension across points 1 and 2, the correct answer of 17.8 kg is obtained.
  • #1
neoking77
31
0

Homework Statement


The figure shows two masses hanging from a steel wire. The mass of the wire is 60.0 g. A wave pulse travels along the wire from point 1 to point 2 in 24.0 ms.

What is mass m?
knight_Figure_20_80.jpg

Homework Equations


v = sqrt(Ts/mu)

The Attempt at a Solution


T=mu*v^2

t = 0.024s
d = 4m
v = d/t = 166.666m/s

mu = m/L = 60g/8m = 7.5

T = 208331Nsin40 = mg
m = 208331Nsin40/g
m = 13.66

but the answer is 17.8kg. where did i go wrong?
 
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  • #2
the tension that you get from

T=mu*v^2

(I get 209 N - it is 60 grams) is the x-component of the tension in the inclined part of the wire.
 
  • #3
Convert 60 g to kg and try again.
 
  • #4
By using Lami's theorem You can find tension across point 1 and 2.
T/cos40 = mg/sin40. Hence T = mg*cot40.
m = (7.5^-3*166.67^2)/9.8*cot40
= 17.8kg.
 

Related to Tension of String/ Mass question

What is the relationship between tension of a string and its mass?

The tension of a string is directly proportional to its mass. This means that as the mass of the string increases, the tension also increases. This relationship is known as Hooke's Law.

How does the length of a string affect its tension?

The length of a string does not affect its tension, as long as the string remains inelastic and the tension remains constant. However, if the string is elastic or the tension changes, the length of the string can affect its tension.

What factors can change the tension of a string?

The tension of a string can be affected by various factors such as the length, mass, and elasticity of the string. It can also be changed by external forces acting on the string, such as weight or tension applied at the ends of the string.

How does tension affect the vibration of a string?

Tension plays a crucial role in the vibration of a string. The higher the tension, the faster the string will vibrate and produce a higher frequency sound. This is why tightening the strings of a guitar produces a higher pitch sound.

What are some real-life applications of understanding tension of a string and its mass?

Understanding the relationship between tension and mass of a string is important in various fields such as music, engineering, and physics. It helps in designing musical instruments, calculating the strength and stability of structures, and understanding the dynamics of mechanical systems.

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