A60 year old person has a threshold of hearing of 93.0 db for a sound with frequency f=10,000 hz. by what factor must the intensity of a sound wave of that frequency, audible to a typical young adult, (sound level=43.0 db) be increased so that it is heard by the older person.

12.06 times

Explanation:

The ration of intensity of sound of 93 dB and 43 dB is given as follows

I₁ / I₂ =

I₁ / I₂ = 145.44

The intensity of sound heard by old person is 145.44 times the sound heard by young adult.

We know that intensity of sound is proportional to square of frequency  , ie

I ∝ n²

In order to increase the intensity of later sound 145.44 times , we shall have to increase its frequency √145.44  times or 12.06 times

So 12.06 times is the answer.

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west

blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.