Question

A large ball 2 m in radius is made up of
a rope of square cross section with edge
length 4 mm. Neglecting the air gaps in
the ball, what is the total length of the
rope to the nearest order of magnitude?​

Answer 1

ɪɴᴇʀᴛɪᴀ ɪꜱ ᴛʜᴇ ʀᴇꜱɪꜱᴛᴀɴᴄᴇ ᴏꜰ ᴀɴʏ ᴘʜʏꜱɪᴄᴀʟ ᴏʙᴊᴇᴄᴛ ᴛᴏ ᴀɴʏ ᴄʜᴀɴɢᴇ ɪɴ ɪᴛꜱ ᴠᴇʟᴏᴄɪᴛʏ. ᴛʜɪꜱ ɪɴᴄʟᴜᴅᴇꜱ ᴄʜᴀɴɢᴇꜱ ᴛᴏ ᴛʜᴇ ᴏʙᴊᴇᴄᴛ'ꜱ ꜱᴘᴇᴇᴅ, ᴏʀ ᴅɪʀᴇᴄᴛɪᴏɴ ᴏꜰ ᴍᴏᴛɪᴏɴ. ᴀɴ ᴀꜱᴘᴇᴄᴛ ᴏꜰ ᴛʜɪꜱ ᴘʀᴏᴘᴇʀᴛʏ ɪꜱ ᴛʜᴇ ᴛᴇɴᴅᴇɴᴄʏ ᴏꜰ ᴏʙᴊᴇᴄᴛꜱ ᴛᴏ ᴋᴇᴇᴘ ᴍᴏᴠɪɴɢ ɪɴ ᴀ ꜱᴛʀᴀɪɢʜᴛ ʟɪɴᴇ ᴀᴛ ᴀ ᴄᴏɴꜱᴛᴀɴᴛ ꜱᴘᴇᴇᴅ, ᴡʜᴇɴ ɴᴏ ꜰᴏʀᴄᴇꜱ ᴀᴄᴛ ᴜᴘᴏɴ ᴛʜᴇᴍ.