Two sources of waves, call them A and B, send out waves across ...

[mynx]

Two sources of waves, call them A and B, send out waves across the surface of a lake. The waves from A have crests 1 cm high as measured from the normal undisturbed surface of the water. The waves from B are identical to those from A.
 
  How far is the water displaced at a point where a crest from A crosses a valley from B?
  A) 2 cm upward
  B) zero
  C) 1 cm upward
  D) 1 cm downward
  E) 2 cm downward

Question 2

You push your 2 kg physics book along a tabletop, pushing it with 10 newtons of force. If the book is greased so that friction is negligible, the book's acceleration is
 
  A) zero.
  B) 0.2 m/s2.
  C) infinitely large.
  D) 5 m/s2.
  E) 20 m/s2.

[mjenn52]

Answer to Question 1

B

Answer to Question 2

D