Answer:
Explanation:
The efficiency of a refrigerator is defined in the terms of coefficient of performance (COP).
The ratio of amount of heat in cold reservoir to the work done is termed as the COP.
COP = QL / W
COP = T2 / (T1 - T2)
Where, T1 be the temperature of hot reservoir, T2 be the temperature of cold reservoir.
<h2>Answer: about the same size of the gap or slit</h2>
Diffraction happens when a wave (mechanical or electromagnetic wave, in fact, any wave) meets an obstacle or a slit .When this occurs, the wave bends around the corners of the obstacle or passes through the opening of the slit that acts as an obstacle, forming multiple patterns with the shape of the aperture of the slit.
Note that the principal condition for the occurrence of this phenomena is that the obstacle must be comparable in size (similar size) to the size of the wavelength.
In other words, when the gap (or slit) size is larger than the wavelength, the wave passes through the gap and does not spread out much on the other side, but when the gap size is equal to the wavelength, maximum diffraction occurs.
Therefore:
<h2>Waves diffract the most when their wavelength is <u>about the same size of the gap
</u></h2>
<u />
To develop this problem it is necessary to apply the concepts related to the uni-axial deflection of bodies.
From the expression of Hooke's law we have to
Where,
E= Young's modulus
The strain
And substituting P/A for stress and 
for strain gives that
Where,
P = Force
A = Area
L = Length
Therefore this can be re-arranged to give
If we want to calculate the deformation per unit area then we can also rewrite the equation as
Replacing with our values we have to
Therefore the posion ratio would be
Therefore the Poisson's ratio for this material is 0.4238
Mass=142g
K.E=128 J
Speed or Velocity=?
K.E=1/2*m*v^2
128=1/2*142*v^2
128=72*v^2
v^2=128/72
v^2=1.777
by taking square rt
v= 1.333ms-1
so the speed will be 1.333 ms-1
