With what velocity shoulda rod be moved in the direction inclined at 60° to its length so that apparent contraction of 10 % may be found in the length of rod? 0

With what velocity shoulda rod be moved in the direction inclined at 60° to its length so that apparent contraction of 10 % may be found in the length of rod? 0.872 c 1) 0.672 c 2) 0.772 c 3) 0.972 c 4)