Answer:
Sorry i don't speak Vietnam so i can't help you if you write it in English i will have a chance to help you
Answer:
7.5 seconds
Step-by-step explanation:

Thus, the time required for the object to return to its point of departure is 7.5 seconds.
1 kilogram = 1000 grams
100g • 10 = 1000g
Isaiah would need to put 10 100 gram weights on the scale in order for it to equal 1 kilogram.