Answer:
Crystal structure
Explanation:
The repeated pattern of similar particles in a material is called crystal. Crystal structure is the largest constituent unit of a solid matter.
The fundamental identity of a crystal structure is a unit cell that is formed by the arrangement of atoms or ions in a particular manner. A crystal is defined as a regular, long-ranged repeated arrangement of unit cells.
Crystal have a sharp melting and boiling point and they give a sharp edge on being cut with a knife.
Answer:

Explanation:
For a linear elastic material Young's modulus is a constant that is given by:

Here, F is the force exerted on an object under tensio, A is the area of the cross-section perpendicular to the applied force,
is the amount by which the length of the object changes and
is the original length of the object. In this case the force is the weight of the mass:

Replacing the given values in Young's modulus formula:

Answer:
The value is
Explanation:
From the question we are told that
The length of the crack is
The frequency is
The distance outside the cave that is being consider is
The speed of sound is 
Generally the wavelength of the wave is mathematically represented as

=> 
=> 
Generally for a single slit the path difference between the interference patterns of the sound wave and the center is mathematically represented as

=> 
=> 
Generally the width of the sound beam is mathematically represented as

=> 
=>
Answer:
Explanation:
Let the equilibrium position of third charge be x distance from q₁.
Force on third charge due to q₁
= 9 x 10⁹ x 5 x 10⁻⁹ x 15 x 10⁺⁹ / x²
Force on third charge due to q₂
= 9 x 10⁹ x 2 x 10⁻⁹ x 15 x 10⁺⁹ /( .40-x)²
Both the force will act in opposite direction and for balancing , they should be equal.
9 x 10⁹ x 5 x 10⁻⁹ x 15 x 10⁺⁹ / x² = 9 x 10⁹ x 2 x 10⁻⁹ x 15 x 10⁺⁹ /( .40-x)²
5 / x² = 2 / ( .4 - x )²
Taking square root on both sides
2.236 / x = 1.414 / .4 - x
2.236 ( .4 - x ) = 1.414 x
.8944 - 2.236 x = 1.414 x
.8944 = 3.65 x
x = .245 m
24.5 cm
So the third charge should be at a distance of 24.5 cm from q₁ .