Not sure about 21, but the 1738 is a turned used by a rapper named Fetty Wap in his song called Trap Queen to represent the "Remy Boyz 1738" which they named themselves that after the finest 1738 Remy Martin liquor.
Hope that helps you! :)
Speed of the tip of the minute hand=V=0.0244 cm/s
Explanation:
The angular velocity of the minute hand is given by

T= time period of the minute hand=60 min=3600 s
so ω= 2 π/3600 rad/s
Now linear velocity v= r ω
r= radius of minute hand=14 cm
so v= 14 (2 π/3600)
V=0.0244 cm/s
The frequency of the light source is 1.5 x 10¹⁵ Hz.
<h3>
Frequency of the light source</h3>
The frequency of the light source is determined using the following equations;
c = fλ
where;
c is speed of light
f is the frequency
λ is the wavelength
f = (3 x 10⁸) / (2 x 10⁻⁷)
f = 1.5 x 10¹⁵ Hz
Thus, the frequency of the light source is 1.5 x 10¹⁵ Hz.
Learn more about frequency of light here: brainly.com/question/10728818
First speed = 20km/h
Time = 3 hours
Distance = 3×20
<h3> = <u>60 km</u></h3>
Second speed = 30km/h
Time = 4 hours
Distance = 4×30
<h3> = <u>120 km</u></h3>
Total distance = 60+120 = <u>180km</u>
Total time = 3+4 =<u> 7 hours</u>
Average speed = 180/7
<h3> = <u>25.71</u><u> </u><u>km</u><u>/</u><u>h</u></h3>
Hope this will help...
A. Using a combination lens made up of lenses, each of which has a different index of refraction. Is the correct answer.