The correct choice is
D. 22 Hz and 42 Hz.
In fact, the beat frequency is given by the difference between the frequencies of the two waves:
In this problem, the beat frequency is 
, therefore the only pair of frequencies that gives a difference equal to 20 Hz is
D. 22 Hz and 42 Hz.
The bottleneck event of the plants in an area results in secondary succession.
<h2>What is bottleneck event?</h2>
A bottleneck is an event that drastically reduces the population size of an organism. The bottleneck may be caused by various events, such as an environmental disaster, the hunting or habitat destruction that results in the deaths of organisms.
<h3>Secondary succession</h3>
Secondary succession is a type of ecological succession in which plants and animals recolonize a habitat after a major disturbance such as a devastating flood, wildfire, landslide, lava flow, or human activity e.g., farming or road or building construction.
Learn more about succession here: brainly.com/question/1212975
The correct answer is :
Unit vectors I and j along the x-axis and y-axis, respectively, define the Cartesian coordinate system. The radial unit vector r, which indicates the direction from the origin, and the unit vector t, which is orthogonal (perpendicular) to the radial direction, together create the polar coordinate system.
We can obtain the horizontal component by applying the trigonometric identity of Cos(Ф), and if we obtain the component on the x axle, such as 22000 (m)×Cos(51°) = x, we may determine that x = 13845.05 metres. We need to obtain the vector components because we already know the distance and the angle.
To learn more about Cartesian unit-vector refer the link:
brainly.com/question/26776558
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d=vi*t+(1/2)gt²
d=11 m
g=9.8 m/s²
vi=0 m/s
11 m=0 m/s*t+(1/2)9.8 m/s²t²
11 m=4.9 m/s²t²
t²=11 m / 4.9 m/s²
t=√(11 m / 4.9 m/s²)=1.489... s≈1.5 s
Answer: the time the sone is in flight is 1.5 s
Answer: Friction
Explanation:
Friction and the normal force would be the two initial forces to overcome.
