If you run a complete loop around an outdoor track (400 m), in 100 s your average velocity is 0.25 m/'s 40 m's 400-0mb zero All of the following are scalars, except mass force temperature distance Can an object's velocity change direction when its acceleration is constant? No, this is not possible because it is always speeding up b. No, this is not possible because it is always speeding up or always slowing down, but it can never turn around. Yes, this is possible, and a rock thrown straight up is an example Yes, this is possible, and a car that starts from rest, speeds up, slows to a stop, and then backs up is an example. 4. Which graph represents an object at rest? A) B) D) X X X t + t When an object is released from rest and falls in the absence of friction, which of the following is true concerning its motion? It's acceleration is constant Its velocity is constant Neither its acceleration nor its velocity is constant Both its acceleration and its velocity are constant