Answer:
The kilogram (kg) is defined by taking the fixed numerical value of the Planck constant h to be 6.62607015 ×10−34 when expressed in the unit J s, which is equal to kg m2 s−1, where the meter and the second are defined in terms of c and ∆νCs.
Answer:
Explanation:
As the source is situated on x - axis , it must be situated in between the two listeners .
So the x coordinate of source is
(-7 + 3 )/2
= - 2 m
The equation of the wave- front will be that o a circle having centre at (-2,0)
and radius = distance between -2 and 3 , that is 5 m
equation of circle
=( x+2 )² + y² = 25
It cuts y axis when x = 0
Putting x = 0
4 + y² = 25
y² = 21
y = + √21 , or - √21
Answer:
red shift, indicating that the universe is expanding
Explanation:
Doppler effect occurs when a source of a wave (e.g. light, or sound waves) moves relative to an observer; as a result of this relative motion, the wavelength of the wave appears lengthened/shortened to the observer. Two situations can occur:
- The source of the wave is moving towards the observer - in this case, the wavelength of the wave becomes shorter. If the wave is visible light, such as the light emitted by distant galaxies, this means that the wavelength of the light shifts towards the blue-end of the spectrum (blue-shift)
- The source of the wave is moving away from the observer - in this case, the wavelength of the wave becomes longer. If the wave is visible light, such as the light emitted by distant galaxies, this means that the wavelength of the light shifts towards the red-end of the spectrum (red-shift)
In our universe, we observe a red-shift for all the distant galaxies: this means that these galaxies are moving away from us, so this is an indication that the universe is expanding.
Answer:
Due to equal pressure in all the direction at a particular level in a fluid medium (Pascal's Law)
Explanation:
We are not crushed by the weight of the atmosphere because atmosphere is a fluid and we are immersed into it. So, according to the Pascal's law the the pressure a each point in a horizontal level is equal in all the direction irrespective of the orientation of a body.
Variation of pressure in term of the height of a fluid medium is given as:
density of fluid
g = acceleration due to gravity
h = height of the free surface of the fluid from the immersed object.
- And atmosphere has very less variation of pressure with change in height as it is a rare medium fluid and so for a human height there is very negligible variation of pressure at the heat of a human with respect to his toe.
Answer:
A) 
B) 
C) 
D) mosquitoes speed in part B is very much larger than that of part C.
Explanation:
Given:
- Distance form the sound source,
- sound intensity level at the given location,
- diameter of the eardrum membrane in humans,
- We have the minimum detectable intensity to the human ears,
(A)
<u>Now the intensity of the sound at the given location is related mathematically as:</u>
..........................................(1)
<em>As we know :</em>
is the energy transferred to the eardrums per second.
(B)
mass of mosquito, 
<u>Now the velocity of mosquito for the same kinetic energy:</u>
(C)
Given:
- Sound intensity,
<u>Using eq. (1)</u>
Now, power:
Hence:
(D)
mosquitoes speed in part B is very much larger than that of part C.
