What is a period and how does it work

A period is a form of grammer , and it is used to end a sentence 

A period can be the veritcal columns designating elements on the periodic table.

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 

All are great precautions but you can still lift lighter and different muscles in between hard workdays. this keeps other muscles not usually used in shape.