Answer:
<u>because of the doppler effect</u>
Explanation:
<em>Remember</em>, the doppler effect refers to the changes in sound (frequency of sound) observed by a person who is in a position relative to the wave source.
In this example, we notice as the train comes closer to the boy, the sound becomes louder also increasing the pitch slightly, the doppler effect sets in when the train passes the boy because the boy notices a decrease in the pitch of the moving train.
We learn from the change in the observed sound of the train that the frequency of the sound is determined by the distance of the observer from the wave source.
In other words, the closer the source of the sound to the observer; the faster it travels to the observer, however, the farther it is; the lesser it is; the greater the sound heard.
Answer:
3.82 Hertz
Explanation:

This is the equation of a wave which varies sinusoidally.
The standard equation of a wave is given by

where, A be the amplitude of the wave, k be the wave number, x be the displacement of wave, ω be the angular frequency and t be the time taken, and Ф be the phase angle.
now compare the given equation by the standard equation, we get
k = 3
ω = 24
Ф = π / 2
So, the angular frequency = 24
The relation between the angular frequency and the frequency is given by
ω = 2 x π x f
24 = 2 x 3.14 x f
f = 3.82 Hertz
Answer:
9.8 Newton
Explanation:
At average gravity on earth (conventionally, g=9.80665m/s2),
a kilogram mass exerts a force of about 9.8 newton
I hope this answer helps you
469.24m. An airplane flying 60m/s at a height of 300m dropped a sack of flour that stack the ground 469.24m from the point of release.
This is a example of horizontal parabolic projectile motion,and we represents this motion in the coordinate axis, which means that the velocity has components in x axis and y axis.
The equation of components on the x axis.
, where x is the distance and Vox the initial velocity before the drop
The equation of components on the y axis.
, where y is the height, and the velocity in y component before the drop is 0, reducing the equation to 
Clear t from both the equation of components on the x axis and the y axis:
and 
Equating both equations and clearing the distance x:

Substituting the values:

Answer:
Explanation:
Long screwdrivers are easier to turn because the grip is in the palm of the hand, thus allowing all fingers to contribute. A shorter screwdriver is turned with the thumb and first two or three fingers, providing much less torque.