Answer:
The range of wavelengths of the sound is 7692.30 m and 3846.15 m
Explanation:
A bat emits pulses of sound at a frequency between 39 kHz and 78 kHz. It is required to find the range of wavelengths of this sound.
Bat uses ultrasonic waves. It moves with the speed of light.
If f = 39 kHz,
![\lambda=\dfrac{c}{f}\\\\\lambda=\dfrac{3\times 10^8}{39\times 10^3}\\\\\lambda=7692.30\ m](https://tex.z-dn.net/?f=%5Clambda%3D%5Cdfrac%7Bc%7D%7Bf%7D%5C%5C%5C%5C%5Clambda%3D%5Cdfrac%7B3%5Ctimes%2010%5E8%7D%7B39%5Ctimes%2010%5E3%7D%5C%5C%5C%5C%5Clambda%3D7692.30%5C%20m)
If f = 78 kHz,
![\lambda=\dfrac{c}{f}\\\\\lambda=\dfrac{3\times 10^8}{78\times 10^3}\\\\\lambda=3846.15\ m](https://tex.z-dn.net/?f=%5Clambda%3D%5Cdfrac%7Bc%7D%7Bf%7D%5C%5C%5C%5C%5Clambda%3D%5Cdfrac%7B3%5Ctimes%2010%5E8%7D%7B78%5Ctimes%2010%5E3%7D%5C%5C%5C%5C%5Clambda%3D3846.15%5C%20m)
So, the range of wavelengths of the sound is 7692.30 m and 3846.15 m.
An airplane is flying at a constant speed in a positive direction. It slows down when it approaches the airport where it's going to land. this is an example of negative acceleration (D).
Answer:
The work done is "2000 J".
Explanation:
The given values are:
Force,
F = 200 N
Mass,
m = 55 kg
Displacement,
d = 10 m
Now,
The work done will be:
⇒ ![Work \ done= Force\times displacement](https://tex.z-dn.net/?f=Work%20%5C%20done%3D%20Force%5Ctimes%20displacement)
On substituting the given values, we get
⇒ ![=200\times 10](https://tex.z-dn.net/?f=%3D200%5Ctimes%2010)
⇒ ![=2000 \ J](https://tex.z-dn.net/?f=%3D2000%20%5C%20J)