One mole of nickel (6 x 10²³atoms) has a mass of 59 grams, and its density is 8.9 grams per cubic centimeter so the center-to-center distance between atoms is 2.23 x 10⁻¹⁰ m. You have a long thin bar of nickel, 2.7 m long, with a square cross-section, 0.06 cm on a side.
You hang the rod vertically and attach a 27 kg mass to the bottom, and you observe that the bar becomes 1.38 cm longer. From these measurements, it is possible to determine the stiffness of one interatomic bond in nickel.
What is the spring stiffness of the entire wire, considered as a single macroscopic (large scale), very stiff spring?

Ireally don’t know

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 

Amagnetic field "does not" interact with stationary electric charges. so, a.hope my answer you : )