Một vật được thả rơi tự do với g=10m/s2. Cũng tại nơi ấy 0,5s sau người ta thả vật thứ 2. Tìm thời gian chạm đất và độ cao nơi thả vật.

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 

Amicroscope, because these cells are so small that you would not be able to see them, or what they attack without it.