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Answer:
t=4.86s
Explanation:
To find the wavelength you use the following formula:

v: speed of sound = 343m/s
f: frequency = 400Hz
λ: wavelength of the sound
By doing λ the subject of the formula and replacing the values of f and v you obtain:

Now, to calculate the time that sound takes to reach the last row you use:

t: time
d: distance to the last row = 1947m

hence, the time is 4.86s
8a2-10ab+15b+10 Explaintion:
Answer:
(a). Z = 54.54 ohm
(b). R = 36 ohm
(c). The circuit will be Capacitive.
Explanation:
Given data
I = 2.75 A
Voltage = 150 V
rad = 48.72°
(a). Impedance of the circuit is given by


Z = 54.54 ohm
(b). We know that resistance of the circuit is given by

Put the values of Z &
in above formula we get

R = 36 ohm
(c). Since the phase angle is negative so the circuit will be Capacitive.
<h2>Acceleration due to gravity in moon is 1.5 m/s²</h2>
Explanation:
We have equation of motion s = ut + 0.5 at²
Here the ball travels 3 m less distance in fifth second compared to third second.
That is
s₃ = s₅ + 3
Now we have
Distance traveled in third second, s₃ = u x 3 - 0.5 x g x 3² - u x 2 - 0.5 x g x 2²
s₃ = u - 2.5 g
Also
Distance traveled in fifth second, s₅ = u x 5 - 0.5 x g x 5² - u x 4 - 0.5 x g x 4²
s₅ = u - 4.5 g
That is
u - 2.5 g = u - 4.5 g + 3
2 g = 3
g = 1.5 m/s²
Acceleration due to gravity in moon = 1.5 m/s²