Answer:
Weight needed to balance the bar is 
Explanation:
Given the weight of the bar is 
The length of the bar is 
The weight of the bar will be uniformly distributed over the entire span. We will consider this as a point load acting in the middle of span length, which is at a distance of
from both ends.
Now applying momentum equation about balanced load we get, (see attachment)

The printing press had dramatic effects on European civilization. Its immediate effect was that it spread information quickly and accurately. This helped create a wider literate reading public.
Answer:
Speed of sound inside metal is ≅ 8200 
Explanation:
Given :
Length of metal bar
m
From general velocity equation,

Where
speed of sound in air = 343 
For finding time from above equation,


sec
Since pulses are separated by
sec
So we take time difference,

So speed of sound in metal is,



<span>As it is uniform circular motion therefore speed is constant. Therefore we can rule out option B. Also in circular motion the direction of velocity vector changes therefore velocity can't be constant. Therefore option B is incorrect as well. Also centripetal acceleration is always towards the center so option D is wrong as well.
That implies
option A is correct.</span>