Answer:
Length of the string = 0.24 m
Explanation:
The frequency (f) of vibration of stringed instruments is related to the Tension (T) in the spring by the relation
fₙ = (n/2L)√(T/μ)
where n = 1,2,3,4...
For third harmonic frequency, n = 3
L = length of the string = ?
T = tension in the string = 2.3 N
μ = linear density = 4.6 × 10⁻³ kg/m
f = frequency = 140 Hz
L = (n/2f)√(T/μ)
L = (3/(2×140))√(2.3/0.0046) = 0.40 m
Turning on a light switch converts mechanical energy to electrical and radiant energy. So Mechanical energy
Energy required = mass x specific heat x temperature difference
= 0.5 x 4.19x10^3 x 2
= 4190J
