The frequency of a wave becomes higher due to the object moving at a fast pace coming towards you with shorter wavelengths (depending on the speed) aka the Doppler Effect.
Hope this helps
You told your insane friend that it will take the book 5.6 s to get to the ground.
From the question given above, the following data were obtained:
Height (H) = 155 m
<h3>Time (t) =? </h3>
<u>NOTE</u>: Acceleration due to gravity (g) = 10 m/s²
The time taken for the book to get to ground can be obtained as follow:
<h3>H = ½gt²</h3>
155 = ½ × 10 × t²
155 = 5 × t²
<h3>Divide both side by 5</h3>

t² = 31
<h3>Take the square root of both side </h3>

<h3>t = 5.6 s</h3>
Thus, the time taken for the book to get to the ground is 5.6 s
Hence, you told your insane friend that it will take the book 5.6 s to get to the ground.
Learn more: brainly.com/question/24903556
Answer:
23.67 m
Explanation:
We are given;
Frequency; f = 0.3 Hz
Speed; v = 7.1 m/s
Now, formula to get the wavelength is from the wave equation which is;
v = fλ
Where λ is wavelength
Making λ the subject, we have;
λ = v/f
λ = 7.1/0.3
λ = 23.67 m
Answer:
Minimum speed will be equal to 2.213 m/sec
Explanation:
We have given radius of the r = 2 m
Coefficient of friction 
At minimum speed frictional force will be equal to centripetal force
So 


So the minimum speed will be equal to 2.213 m/sec