Question

What is the minimum distance of an echo to occur​

Answer 1

Answer: The velocity of sound in dry air is approximately 343 m/s at a temperature of 25 °C. Therefore, the reflecting object must be more than 17.2m from the sound source for echo to be perceived by a person located at the source.

Explanation:

Answer 2

「ᴛʜᴇ ᴠᴇʟᴏᴄɪᴛʏ ᴏғ sᴏᴜɴᴅ ɪɴ ᴅʀʏ ᴀɪʀ ɪs ᴀᴘᴘʀᴏxɪᴍᴀᴛᴇʟʏ 343 m/s ᴀᴛ ᴀ ᴛᴇᴍᴘᴇʀᴀᴛᴜʀᴇ ᴏғ 25 °ᴄ. ᴛʜᴇʀᴇғᴏʀᴇ, ᴛʜᴇ ʀᴇғʟᴇᴄᴛɪɴɢ ᴏʙᴊᴇᴄᴛ ᴍᴜsᴛ ʙᴇ ᴍᴏʀᴇ ᴛʜᴀɴ 17.2ᴍ ғʀᴏᴍ ᴛʜᴇ sᴏᴜɴᴅ sᴏᴜʀᴄᴇ ғᴏʀ ᴇᴄʜᴏ ᴛᴏ ʙᴇ ᴘᴇʀᴄᴇɪᴠᴇᴅ ʙʏ ᴀ ᴘᴇʀsᴏɴ ʟᴏᴄᴀᴛᴇᴅ ᴀᴛ ᴛʜᴇ sᴏᴜʀᴄᴇ.」♡

⠀ ⠀⠀ ⠀ ⠀⠀ ⠀

⠀ ⠀⠀ ⠀ ⠀⠀ ⠀

⠀ ⠀⠀ ⠀ ⠀⠀ ⠀

⠀ ⠀⠀ ⠀ ⠀⠀ ⠀

⠀ ⠀⠀ ⠀ ⠀⠀ ⠀

⠀ ⠀⠀ ⠀ ⠀⠀ ⠀

⠀ ⠀⠀ ⠀ ⠀⠀ ⠀

Hope its help uhh :)