If \(L^{3}_{0}\) is the rest volume of a cube, then volume viewed from a reference frame moving with uniform velocity v in a direction parallel to an edge of the cube is

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UP LT Grade Teacher (Science) 2018 Official Paper
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  1. \(L_0^3\)
  2. \(L_0^3 \left(1-\frac{v^2}{c^2}\right)^ {\frac{3}{2}}\)
  3. \(L_0^3 \left(1-\frac{v^2}{c^2}\right)^{\frac{1}{2}}\)
  4. \(L_0^3 \left(1-\frac{v^2}{c^2}\right)^{3}\)

Answer (Detailed Solution Below)

Option 3 : \(L_0^3 \left(1-\frac{v^2}{c^2}\right)^{\frac{1}{2}}\)
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Detailed Solution

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Calculation:

Given that the reference frame is moving parallel to one edge of the cube:

The length along the direction of motion will contract according to the formula. L = L0 × (1 - v2 / c2)1/2 

 Here, L0 is the rest length and L is the contracted length.

However, the lengths perpendicular to the direction of motion remain unchanged.

Volume of the cube is:

V = Length × Width × Height

In this case:

Length along the direction of motion = L0 × (1 - v2 / c2)1/2

Width and Height remain = L0

⇒ V = L0 × (1 - v2 / c2)1/2 × L0 × L0

⇒ V = L03 × (1 - v2 / c2)1/2

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