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Q1 In an experiment on standing waves, a string 90 cm long is

attached to the prong of an electrically driven tuning fork that oscillates

perpendicular to the length of the string at a frequency of 60 Hz. The

mass of the string is 0.044 kg. What tension must the string be under if it

is to vibrate in four loops?

I used the formula L=4(λ/2) giving 2λ=L L=1.8m

V=fλ v=108m/s then using the formula v=sq root(T/μ) giving me a tension of 279.936N Is this correct

Q2 Two sinusoidal waves with the same amplitude, frequency and

speed, travel in the same direction along a string and interfere with one

another to produce a resultant wave with a displacement

y = (3.0 x 10-3) sin(20x - 4.0t + 0.6) cos(0.6) m. What is (a) the amplitude

and (b) the wavelength of the waves and (c) the phase difference

between them?

Wave is in the form y'(x,t)=[2ym(cos(tetha/2)sin(Kx-wt+1/2(tetha)tetha/2

y'm=2ymcos1/2tetha

answer 1.13mm is this correct?

k=20 rad/m

w=4 rad/s

λ=2pi/k

=2pirad/20rad/m

=31.4cm

T=2pi/w

=1.57seconds

f=1/t

=0.6366hz

I know this is wrong please lead me in the right direction