Answer:
Apparent depth (Da) = 60.15 cm (Approx)
Explanation:
Given:
Distance from fish (D) = 80 cm
Find:
Apparent depth (Da)
Computation:
We know that,
Refractive index of water (n2) = 1.33
So,
Apparent depth (Da) = D(n1/n2)
Apparent depth (Da) = 80 (1/1.33)
Apparent depth (Da) = 60.15 cm (Approx)
Answer:
v= 2413.5 m/s
Explanation:
maximum change of speed of rocket
=(initial exhaust velocity)×ln [(initialmass/finalmass)]
let initial mass= m
final mass = m-m(4/5) = m/5
[since the 80% of mass which is fuel is exhausted]
V-0 = 1500 ln (1/0.2)
V= 1500×1.609 = 2413.5 m/s
therefore, its exhaust speed v= 2413.5 m/s
Answer:
0.83 m or 5.57 m
Explanation:
Destructive interference will occur when the distances from the speakers differ by 1/2 wavelength.
The length of 1 cycle of 72.4 Hz is ...
λ = v/f = (343 m/s)/(72.4 Hz) ≈ 4.738 m
So, the distance of the listener from speaker B is ...
3.2 m ± (4.738 m)/2 = {0.83 m, 5.57 m} . . . either of these distances
_____
The location could be at additional multiples of 4.738 m, but we think not. The sound intensity drops off with the square of the distance from the speaker, so identical sound waves from the speakers will sound quite different at different distances from the speakers. For best interference, the distances need to be as close to the same as possible. That will be at 3.2 m and 5.57 m.
_____
<em>Comment on the speed of sound</em>
We don't know what speed you are to use for the speed of sound. We have used 343 m/s. Some sources use 340 m/s, which will give a result different by 2 or 3 cm.
The neutral pH is 7. Less than 7 indicates an acid and more than 7 indicates a base (up to 14).
<span>
NaCl - it's a salt (we can't measure the pH)
H2O - it can be an acid but also a base (the pH it is almost neutral,meaning close to 7 )
HF - it is a strong acid
</span><span>
KOH
- it is a strong base (pH=14)
</span>
↓
He needs to use HF (Hydrogen fluoride) to decrease the pH.