Here is your answer
b) 
REASON :
We know that
Velocity= Frequency× Wavelength
So,
Frequency= Velocity/wavelength
Here,
V= 3× 10^8 m/s
Wavelength= 2×10^-3 m
Hence,
Frequency= 3×10^8/2×10^-3
= 3/2 × 10^11
= 1.5× 10^11 Hz
HOPE IT IS USEFUL
Answer:
For the given conditions the fundamental frequency is 3728.26 Hertz
Explanation:
We know that for a pipe open at one end and closed at other end the fundamental frequency is given by

where
f is the fundamental frequency
is the speed of sound in air in the surrounding conditions.
L = Length of the pipe
Applying values we get and using speed of sound as 343m/s we get

Answer:
The two forces that affect on the pendulum are the force of gravity,
Explanation:
- ⇒ There is the force of gravity that acts downward upon the bob. It results from the Earth's mass attracting the mass of the bob. And there is a tension force acting upward and towards the pivot point of the pendulum.
Therefore, I hope this helps!
Answered by: 
Answer: The acceleration of the object is 0.67m/s^2 west.
Explanation: Here we are given the initial velocity and final velocity as well as the time taken. Acceleration is the change in velocity per unit time, thus the equation becomes.
a=dv/t
a=vf-vi/t
a=-2.1-4.7/3.9
a= 0.66m/s^2 west
10 mph/s because there is 60 seconds in a minute then divide by 6 which is 10.