1)If 1 = i^ i^ + j^ j^ + k^ k^
Write out the expression for 1 × D
Ans.
1
× D = i^ Dx +
j^ Dy + k^ Dz
2. a) Provide a matrix which satisfies: i^ i^ + j^ j^ + k^ k^ = 7/2
The trace must equal to 7/2 so the diagonal elements need to yield that sum. Thus:
The trace must equal to 7/2 so the diagonal elements need to yield that sum. Thus:
(1/2......0........0)
(0........1........0)
(0........0....... 2)
is one example of a matrix that satisfies the condition
b) Write out the trace for the metric tensor.
Ans. The metric tensor is:
g ik
=
(1.....0...............0)
(0.....r2...............0)
(0.....0........r2 sin f)
(0.....r2...............0)
(0.....0........r2 sin f)
Then the trace (Tr) =
1 + r2 + r2 (sin f)= 1 + r2 (1 + sin f)
c) Give one example of 3 x 3 tensor, then show how it might contain an anti-symmetric and symmetric tensor (also how to go from one form to the other).
Ans. Let a i j =
(2......3........2)
(5........7.......-2)
(4........-4....... 0)
Then the antisymmetric form is: a j i =
(0......3........-4)
(-3.......0.......-2)
(4........2....... 0)
Then the symmetric part is the difference: a i j - a j i =
(2......0........6)
(8......7........0)
(0......-6....... 0)
3. Find the trace of each matrix given:
Soln. simply add the diagonal elements for each, i.e.
a) Tr = 2 + 8
p + p = 2 + 9 p
b) Tr = 2 r + 2 L + r /2 = 5 r /2 + 2L
c) Tr = p + p/ 3 + p/ 6 + p/7 = 69p / 42
No comments:
Post a Comment