Answer: Varying amounts of the Moon's lit surface being visible from Earth.
Explanation:
Phases of the moon can be defined as the different shapes of the moon visible from the Earth. This happens because sun lits up the face of moon and due to different position of moon in the orbit around earth, varying portion of the lit surface of the moon is visible from Earth. Refer to the diagram below:
Answer:
Surely Achilles will catch the Tortoise, in 400 seconds
Explanation:
The problem itself reduces the interval of time many times, almost reaching zero. However, if we assume the interval constant, then it is clear that in two hours Achilles already has surpassed the Tortoise (20 miles while the Tortoise only 3).
To calculate the time, we use kinematic expression for constant speed:
The moment that Achilles catch the tortoise is found by setting the same final position for both (and same time as well, since both start at the same time):