The frequency of the wave is 6800 Hz
<u>Explanation:</u>
Given:
Wave number, n = 20
Speed of light, v = 340 m/s
Frequency, f = ?
we know:
wave number = 

Therefore, the frequency of the wave is 6800 Hz
Here's a quick way to find out. Pick up your glasses, bifocals work best, and find the focal length with a flashlight against a book. If I remember right, the object should be magnified and upside down. So, A.
Answer: The physics of evolution had made the moon like it is today....Please watch this video from you tube about the evolution of the moon.
Explanation:
https://youtu.be/UIKmSQqp8wY
Answer:
Work done by external force is given as

Explanation:
As per work energy Theorem we can say that work done by all force on the car is equal to change in kinetic energy of the car
so we will have

now we have


so from above equation

so from above equation work done by external force is given as
