Answer:
They can't hear an echo in small room because in it the sound can't be reflected back. For an echo of a sound to be heard,the minimum distance between the source of sound and the walls of the room should be 17.2 m.
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To solve this problem it is necessary to apply the concepts related to the principle of superposition and the equations of destructive and constructive interference.
Constructive interference can be defined as

Where
m= Any integer which represent the number of repetition of spectrum
= Wavelength
d = Distance between the slits.
= Angle between the difraccion paterns and the source of light
Re-arrange to find the distance between the slits we have,



Therefore the number of lines per millimeter would be given as



Therefore the number of the lines from the grating to the center of the diffraction pattern are 380lines per mm
Here we can use coulomb's law to find the force between two charges
As per coulombs law
]tex]F = \frac{kq_1q_2}{r^2}[/tex]
here we have




now by using the above equation we have


so here the force between two charges is of above magnitude and this will be repulsive force between them as both charges are of same sign.
Answer:
B
Explanation:
because if grocery store has a weak stability it will collapse when face strong naturally weather
Answer:
If an object has a fast velocity, the dots on a ticker tape diagram will be far apart.