There are no inaccurate items on the list you provided.
And what does 'the following" mean anyway ?
Answer:
Explanation:
The frequency of a simple pendulum is given by:
where
g is the acceleration of gravity
L is the length of the pendulum
Calling 
the length of the first pendulum and 
the acceleration of gravity at the location of the first pendulum, the frequency of the first pendulum is
The length of the second pendulum is 0.4 times the length of the first pendulum, so
while the acceleration of gravity experienced by the second pendulum is 0.9 times the acceleration of gravity experienced by the first pendulum, so
So the frequency of the second pendulum is
Therefore the ratio between the two frequencies is
The coordinate system should have the origin at the point where the feather is dropped and the downward direction is to be taken as positive.
All falling bodies experience acceleration towards the center of the Earth due to the force of gravitational attraction exerted on the object by the Earth. A feather, when dropped experiences an acceleration in the downward direction. Since the acceleration of the feather is in the downward direction, a feather, when dropped with zero initial velocity, has its velocity vector directed in the direction of its acceleration.
If the downward direction is taken as positive, the falling feather can be said to have a positive velocity and a positive acceleration.
Its “A“ primary waves!!!!!!
