How fast must a meter stick move, relative to the frame of the ...

[jayhills49]

How fast must a meter stick move, relative to the frame of the observer making the measurement, so its length will be measured to be 0.60 m?
 
  A) 0.40c B) 0.90c C) 0.70c D) 0.80c E) 0.60c

Question 2

A proton, moving in a uniform magnetic field, moves in a circle perpendicular to the field lines and takes time T for each circle. If the proton's speed tripled, what would now be its time to go around each circle?
 
  A) 9T
  B) 3T
  C) T
  D) T/3
  E) T/9

[Leostella20]

Answer to Question 1

D

Answer to Question 2

C