00:01
The question is asking to find the intensity of sound at the distance of 3 .6 times the distance where she is standing and also the question is asking to find a sound intensity level at the new distance.
00:12
Let us add the given data given the old distance, the initial distance where she is standing is let us represent with r1 is d meters and the new distance at which the sound intensity need to be found at it.
00:27
Let us denote with r2 is equal to 3 .6 d meters, the intensity of sound at the distance of d meter is i1 is equal to 4 .1 times down power minus 3 watt per meter square.
00:41
We need to find i2 and sound intensity level at i2.
00:48
Let us draw that diagram briefly.
00:51
Here the motor has fixed power.
00:54
So we know i is equal to p by a where i is the intensity of sound.
00:59
A is the spherical area around the motor and p is the power of motor.
01:05
The power of motor is constant.
01:09
I is inverse proportional to 1 by a.
01:12
We know here a is equal to 4 .a.
01:15
A is equal to 4xr square...