*☆*――*☆*――*☆*――*☆*――*☆*――*☆*――*☆*――*☆**☆*――*☆*――*☆*――*☆
Answer: Something that's vibrating, and you also need medium for those vibrations to start in.
I hope this helped!
<!> Brainliest is appreciated! <!>
- Zack Slocum
*☆*――*☆*――*☆*――*☆*――*☆*――*☆*――*☆*――*☆**☆*――*☆*――*☆*――*☆
Answer:
Initial speed = 20 m/s
Final speed = 35 m/s
Time to speed up = 5 seconds
Explanation:
Directly from the information given:
Initial speed = 20 m/s
Final speed = 35 m/s
Time to speed up = 5 seconds