A man walks his dog on a very straight path in a park. He can walk back and forth as slow or fast as he wants to, but he has to stay on the path. Which of the following statements is correct for an arbitrary time interval? a. His average speed can be greater than the magnitude of his average velocity.
b. His average speed can be less than the magnitude of his average velocity.
c. Since he is walking along a straight path, his average acceleration must be zero.
d. His average velocity must be zero.