Which of the situations involve no force of friction? Explain why A. A hockey puck is shot across an ice rink
B. A sky diver falls from a plane
C. A probe travels through deep space
D. A speed boat skims across the water

As newton's first law states a object in motion stays in motion

Answertraveling around a circular trackexplanation"traveling around a circular track" is the best answer as you could be traveling around a circular track at a constant speed. your velocity would therefore have the same magnitude but will always be constantly direction. since acceleration is the rate of change of velocity, the rate of change will only involve the direction of velocity and not the magnitude.wrong choices: "an object at rest" does not accelerate at all"increasing speed while traveling around a curve" means that the acceleration will not be constant due to only change in direction; it will be constant due to both magnitude and direction"an object in free fall" does not necessarily change direction 

Ok what do you need with

Iwould say the answer is d