Can two pool balls, both of them moving, have a total momentum of ...

[tnt_battle]

Can two pool balls, both of them moving, have a total momentum of zero?
 
  A) No, because any moving object has momentum.
  B) No, because they both have energy.
  C) Yes, if they are moving in opposite directions, both with the same speed.
  D) Yes, but only at the instant that they collide.
  E) Yes, if they are both moving outward from the same point.

Question 2

If an x-ray beam of wavelength 1.4  10-10 m makes an angle of 30 with a set of planes in a crystal causing first order constructive interference, what is the plane spacing?
 
  A) 0.28 nm
  B) 0.070 nm
  C) 0.32 nm
  D) 0.16 nm
  E) 0.14 nm

[ynlevi]

Answer to Question 1

C

Answer to Question 2

E

[tnt_battle]

Excellent

[brbarasa]

Gracias!