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Exercises 3.5 Exercise

1.

Show that the symmetric or antisymmetric property of a tensor is conserved under a transformation of coordinates.

2.

Show that the quantities \(\delta_{q}^{p}A_{p}\) transform like the components of a tensor.

3.

Prove that \(\delta_{ik} u_{k} =u_{i}\text{.}\)

4.

If \(A_{ij}\) is an antisymmetric tensor, Show that \(\delta_{j}^{i}A_{ij} =0\text{.}\)

5.

If \(A_{ij}\) is a skewsymmetric tensor of rank two, then prove that \((\delta_{ij}\delta_{lk} +\delta_{il}\delta_{jk})T_{ik} = 0\text{.}\)

6.

Show that if a physical quantity has no component in one coordinate system, then it does not have a component in any other coordinate systems.

7.

How many independent commponents are there in an antisymmetric tensor of rank two?

8.

Show that the direct product of a \(0^{th}\) rank tensor and a \(2^{nd}\) rank tensor is a tensor of rank two.

9.

Prove that the sum of diagonal components of a second-rank tensor is an invariant.

10.

State the transformation properties of tensors \(A_{i}\) and \(B^{ij}\text{.}\) Obtain the transformation properties of \(A_{i}B^{ij}\text{.}\) Explain your result.

11.

Contract and provide direct product of two tensors \(A_{\sigma}^{\mu \nu}\) and \(B_{l}^{m}\text{.}\) What will be the rank of the contracted tensor and the direct product?

12.

Show that any tensor of rank 2 can be expressed as the sum of a symmetric and an antisymmetric tensors of rank 2.
Hint.
Any tensor \(A^{ij}\) of rank 2, may be expressed as
\begin{equation*} A^{ij} = \frac{1}{2}\left(A^{ij}+A^{ji}\right)+\frac{1}{2}\left(A^{ij}-A^{ji}\right) \end{equation*}

13.

\(\vec{\omega}\) is any arbitrary contravarient vector. It is known that \(A_{ij}\vec{\omega}\) is a covariant vector. Show that \(A_{ij}\) is a covariant tensor of rank 2.

14.

Using the inner product of a tensor and applying contraction principle obtain the length L of a tensor \(A^{i}\text{.}\)
Hint.
take direct product of \(A^{i}\) and \(A_{j}\text{.}\)