Answer:
1) Because of the size and time the sound wave moves, an echo is typically transparent and easy to discern. Since reverberations typically don't have enough distance or time to fly, they will pile up on top of each other, making it impossible to understand.
People will detect an echo if the distance between the source of the sound and the reflected body is greater than 50 feet. When a sound wave is bounced off a nearby surface, it may create a reverberation.
2) The speed of sound in hot air is more than that in cold air because air molecules are traveling faster in hot air.
Explanation:
2 is correct hope you get it right
Answer:
A generator converts mechanical energy into electrical energy, while a motor does the opposite - it converts electrical energy into mechanical energy.
Explanation:
I think the correct answer would be the child quietly sits until the timer goes off. It is ineffective because the child would be used to this process and would come to a time where he will not get something from it.Also, it would make a child feel isolated and alone which would affect hi self-esteem in a long run.