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Standard XII

Physics

Need for Intensity

A wire is 4...

Question

A wire is $4 m$ long and has a mass $0.2 k g$ . The wire is kept horizontally. A transverse pulse in generated by plucking one end of the taut (tight) wire. The pulse makes four trips back and forth along the cord in $0.8 s e c$ . The tension is the cord will be

80 N

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160 N

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240 N

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320 N

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Solution

The correct option is A $80 N$
Given,
Length of the wire $l = 4 m$
Mass of the wire $M = 0.2 k g$
Now, displacement $d = 4 (2 \times 4) m = 32 m$
Velocity of waves on a stretched cord
$v = \sqrt{T / μ}$
$μ = \frac{0.2 k g}{4 m} = 0.05$
Now, velocity,
$v = \frac{d}{t} = \frac{32 m \times 10}{0.3 s} = 40 m / s$
$∴$ The tension
$T = v^{2} μ = 40 \times 40 \times 0.05 = 40 \times 40 \times \frac{5}{100} = 16 \times 5 = 80 N$

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A wire is 4 m long and has a mass 0.2 kg. The wire is kept horizontally. A transverse pulse in generated by plucking one end of the taut (tight) wire. The pulse makes four trips back and forth along the cord in 0.8 sec. The tension is the cord will be

The correct option is A 80 NGiven,Length of the wire l=4mMass of the wire M=0.2kgNow, displacement d=4(2×4)m=32mVelocity of waves on a stretched cordv=√T/μμ=0.2kg4m=0.05Now, velocity,v=dt=32m×100.3s=40m/s∴ The tensionT=v2μ=40×40×0.05=40×40×5100=16×5=80N

A wire is $4 m$ long and has a mass $0.2 k g$ . The wire is kept horizontally. A transverse pulse in generated by plucking one end of the taut (tight) wire. The pulse makes four trips back and forth along the cord in $0.8 s e c$ . The tension is the cord will be