Answer:
For the first question, b. For the second, a. For the third, b.
Step-by-step explanation:
1. The answer is "b" because in a vacuum all objects fall at the same rate, they are in free-fall.
2. The answer is "a": the box is at rest before the truck starts moving and remains at rest after it moves because the box is not being acted upon by the friction of the truck bed. See Newton's First Law of Motion.
3. The answer is "b" because your relative velocity would be the bus' velocity minus your velocity, as you are walking in the opposite direction of the bus. Thus, your resultant velocity is
m/s.