Answer:
minimum frequency = 170 Hz
Explanation:
given data
One path long = 20 m
second path long = 21 m
speed of sound = 340 m/s
solution
we get here destructive phase that is path difference of minimum 
here λ is the wavelength of the wave
so path difference will be
21 - 20 =
λ = 2 m
and
velocity that is express as
velocity = frequency × wavelength .............1
frequency = 
minimum frequency = 170 Hz
Answer: Real image
Explanation:
converging lens will only produce a real image if the object is located beyond the focal point (i.e., more than one focal length away).
You take the inverse of the total resistances of each branch and add them up.
So if you have 5ohm, 7 ohm, and 10ohm, you would add
1/5 + 1/7 + 1/10 = 31/70
Then flip it back by either using the <span>x<span>−1</span></span><span> (inverse) key on your calculator or simply dividing 70 by 31 to get a total of 2.26ohms</span>
F=ma
F= 4x1.2
F= 4.8 N
F= 4gsin30 - Friction
Friction= 19.6 - 4.8 N
Friction= 14.8 N
Friction= u x 4gcos30
14.8 / 4gcos30 = u
u= 0.43596...
u= 0.44
coefficient is 0.44
