The dyson sphere is an hypothetical spherical structure centered around a star. inspired by a science fiction story, physicist freeman dyson described such a structure for the first time in a scientific paper in 1959. his basic idea consisted of an artificial spherical structure of matter built around a star at a distance comparable to a planetary orbit, with the purpose of capturing the energy radiated by the star and reusing it for industrial purposes. assume the mass of the sun to be 2.00×1030 kg .

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 

The upward force acting on the wing of a airplane in flight is known as the "lift" force. (d)