Question

A paratrooper falling towards the earth is in state of equilibrium because
a. He experiences no gravitational force b. The air is not blowing
c. He is falling vertically downward
d. Force of gravity is balanced by air friction​

Answer 1

Answer:

ᴛʜᴇʀᴇ ɪꜱ ᴏɴʟʏ ᴏɴᴇ ꜰᴏʀᴄᴇ ᴜᴘᴏɴ ᴛʜᴇ ʙᴀʟʟ - ᴛʜᴇ ꜰᴏʀᴄᴇ ᴏꜰ ɢʀᴀᴠɪᴛʏ. (ᴀɪʀ ʀᴇꜱɪꜱᴛᴀɴᴄᴇ ɪꜱ ɴᴇɢʟɪɢɪʙʟᴇ; ᴛʜᴇ ʙᴀʟʟ ɪꜱ ɴᴏᴛ ᴏɴ ᴀ ꜱᴜʀꜰᴀᴄᴇ, ꜱᴏ ᴛʜᴇʀᴇ ɪꜱ ɴᴏ ꜰʀɪᴄᴛɪᴏɴ ᴏʀ ɴᴏʀᴍᴀʟ ꜰᴏʀᴄᴇ; ᴛʜᴇ ᴀᴘᴘʟɪᴇᴅ ꜰᴏʀᴄᴇ ᴡʜɪᴄʜ ᴘʀᴏᴊᴇᴄᴛꜱ ɪᴛ ɪɴᴛᴏ ᴍᴏᴛɪᴏɴ ᴅᴏᴇꜱ ɴᴏᴛ ᴀᴄᴛ ᴜᴘᴏɴ ᴛʜᴇ ʙᴀʟʟ ᴅᴜʀɪɴɢ ɪᴛꜱ ᴛʀᴀᴊᴇᴄᴛᴏʀʏ; ᴛʜᴇʀᴇ ᴀʀᴇ ɴᴏ ꜱᴘʀɪɴɢꜱ, ꜱᴛʀɪɴɢꜱ, ᴡɪʀᴇꜱ, ᴏʀ ᴄᴀʙʟᴇꜱ ᴀᴛᴛᴀᴄʜᴇᴅ ꜱᴏ ᴛʜᴇʀᴇ ɪꜱ ɴᴇɪᴛʜᴇʀ ᴀ ᴛᴇɴꜱɪᴏɴ ꜰᴏʀᴄᴇ ɴᴏʀ ᴀ ꜱᴘʀɪɴɢ ꜰᴏʀᴄᴇ.) ᴛʜᴇ ꜰᴏʀᴄᴇ ᴏꜰ ɢʀᴀᴠɪᴛʏ ᴀᴄᴛꜱ ᴅᴏᴡɴᴡᴀʀᴅ ᴡɪᴛʜ ᴀ ᴍᴀɢɴɪᴛᴜᴅᴇ ᴏꜰ ᴍ•ɢ = (0.250 ᴋɢ) •(9.8 ᴍ/ꜱ/ꜱ) = 2.45 ɴ. ᴛʜᴇ ɴᴇᴛ ꜰᴏʀᴄᴇ ɪꜱ 2.45 ɴ; ᴡʜᴇɴ ᴅɪᴠɪᴅᴇᴅ ʙʏ ᴍᴀꜱꜱ, ᴛʜᴇ ᴀᴄᴄᴇʟᴇʀᴀᴛɪᴏɴ ᴄᴀɴ ʙᴇ ꜰᴏᴜɴᴅ.

ᴀ = ꜰɴᴇᴛ / ᴍ = (2.45 ɴ, ᴅᴏᴡɴ) / (0.250 ᴋɢ) = 9.8 ᴍ/ꜱ/ꜱ, ᴅᴏᴡɴ

Explanation:

ᎻϴᏢᎬ ᎷᎽ ᎪΝՏᏔᎬᎡ ᏆՏ ᎻᎬᏞᏢҒႮᏞ ҒϴᎡ ᎽϴႮ (◕ᴗ◕✿)

Answer 2

Answer:

d. Force of gravity is balanced by air friction

Hope it helps you.