Question

1. why do you fall in forward direction when a moving bus brakes to stop and fall backwards when it accelerates from rest?

Answer 1

All this happens due to inertia.

when brakes are applied, our feet which are in contact with the floor of bus comes to hault instantly but not our rest of the body it stays in motion for some time due to inertia of motion , same happens during sudden acceleration where our feet suddenly comes into motion while the rest of the body is in rest.

Answer 2

ɪɴɪᴛɪᴀʟʟʏ, ᴡʜᴇɴ ᴛʜᴇ ʙᴜs ᴀᴄᴄᴇʟᴇʀᴀᴛᴇs ɪɴ ᴀ ғᴏʀᴡᴀʀᴅ ᴅɪʀᴇᴄᴛɪᴏɴ ғʀᴏᴍ ᴀ sᴛᴀᴛᴇ ᴏғ ʀᴇsᴛ, ᴛʜᴇ ᴘᴀssᴇɴɢᴇʀs ᴇxᴘᴇʀɪᴇɴᴄᴇ ᴀ ғᴏʀᴄᴇ ᴇxᴇʀᴛᴇᴅ ᴏɴ ᴛʜᴇᴍ ɪɴ ᴛʜᴇ ʙᴀᴄᴋᴡᴀʀᴅ ᴅɪʀᴇᴄᴛɪᴏɴ ᴅᴜᴇ ᴛᴏ ᴛʜᴇɪʀ ɪɴᴇʀᴛɪᴀ ᴏᴘᴘᴏsɪɴɢ ᴛʜᴇ ғᴏʀᴡᴀʀᴅ ᴍᴏᴛɪᴏɴ.

ᴏɴᴄᴇ ᴛʜᴇ ʙᴜs sᴛᴀʀᴛs ᴍᴏᴠɪɴɢ, ᴛʜᴇ ᴘᴀssᴇɴɢᴇʀs ᴀʀᴇ ɪɴ ᴀ sᴛᴀᴛᴇ ᴏғ ᴍᴏᴛɪᴏɴ ɪɴ ᴛʜᴇ ғᴏʀᴡᴀʀᴅ ᴅɪʀᴇᴄᴛɪᴏɴ. ᴡʜᴇɴ ᴛʜᴇ ʙʀᴀᴋᴇs ᴀʀᴇ ᴀᴘᴘʟɪᴇᴅ, ᴛʜᴇ ʙᴜs ᴍᴏᴠᴇs ᴛᴏᴡᴀʀᴅs ᴀ ᴘᴏsɪᴛɪᴏɴ ᴏғ ʀᴇsᴛ. ɴᴏᴡ, ᴀ ғᴏʀᴄᴇ ɪɴ ᴛʜᴇ ғᴏʀᴡᴀʀᴅ ᴅɪʀᴇᴄᴛɪᴏɴ ɪs ᴀᴘᴘʟɪᴇᴅ ᴏɴ ᴛʜᴇ ᴘᴀssᴇɴɢᴇʀs ʙᴇᴄᴀᴜsᴇ ᴛʜᴇɪʀ ɪɴᴇʀᴛɪᴀ ʀᴇsɪsᴛs ᴛʜᴇ ᴄʜᴀɴɢᴇ ɪɴ ᴛʜᴇ ᴍᴏᴛɪᴏɴ ᴏғ ᴛʜᴇ ʙᴜs. ᴛʜɪs ᴄᴀᴜsᴇs ᴛʜᴇ ᴘᴀssᴇɴɢᴇʀs ᴛᴏ ғᴀʟʟ ғᴏʀᴡᴀʀᴅs ᴡʜᴇɴ ᴛʜᴇ ʙʀᴀᴋᴇs ᴀʀᴇ ᴀᴘᴘʟɪᴇᴅ.