Question

1. Which of the following pair of waves interfere
   constructively? (assumr pi to be the
   ratio between circumference and diameter of
   a circle; i.e pi = 3.14 ). (1 point)
   1. ( )x = 10 sin ( 30t + pi ) and y = 20 sin ( 30t - 6 * pi )
   2. ( )x = 10 sin ( 30t - pi ⁄ 2 ) and y = 20 sin ( 30t + 5 * pi ⁄ 2 )
   3. ( )x = 10 sin ( 30t - pi ) and y = 20 sin ( 30t )
   4. ( )x = 10 sin ( 30t + pi ) and y = 20 sin ( 30t - 2 * pi )
   5. ( )x = 10 sin ( 30t - pi ) and y = 20 sin ( 30t + 3 * pi )
2. According to special theory of relativity (1 point)
   1. ( )as speed increases time interval increases.
   2. ( )the speed of light depends on the speed of its
      source.
   3. ( )as speed increases mass decreases.
   4. ( )as speed increases length increases.
   5. ( )Mass and energy are equivalent and interchangeable

PLEASE HELP ME SOLVE BOTH PROBLEMS THANKS

Answer 1