Question

under what condition the law of conservation of momentum hold

Answer 1

For a collision occurring between object 1 and object 2 in an isolated system, the total momentum of the two objects before the collision is equal to the total momentum of the two objects after the collision.

NO EXTERNAL FORCE SHOULD BE ACTING ON THE SYSTEM such as gravity friction etc

Answer 2

ᴀɴsᴡᴇʀ࿐

ᴅᴇғɪɴɪᴛɪᴏɴ:-

ᴍᴏᴍᴇɴᴛᴜᴍ ɪs ᴛʜᴇ ᴛʜᴇ ᴀᴍᴏᴜɴᴛ ᴏғ ᴍᴏᴛɪᴏɴ ᴏғ ᴀ ᴍᴏᴠɪɴɢ ʙᴏᴅʏ, ᴍᴇᴀsᴜʀᴇᴅ ᴀs ᴀ ᴘʀᴏᴅᴜᴄᴛ ᴏғ ɪᴛs ᴍᴀss ᴀɴᴅ ᴠᴇʟᴏᴄɪᴛʏ.

=>ᴍᴏᴍᴇɴᴛᴜᴍ= ᴍᴀss × ᴠᴇʟᴏᴄɪᴛʏ

ᴅɪᴍᴇɴsɪᴏɴᴀʟ ғᴏʀᴍᴜʟᴀ ᴏғ ᴍᴏᴍᴇɴᴛᴜᴍ

=>ᴘ = [ᴍ]x [ʟᴛ^(-1)]

ᴄᴏɴsᴇʀᴠᴀᴛɪᴏɴ ᴏғ ᴍᴏᴍᴇɴᴛᴜᴍ:-

ʟᴀᴡ ᴏғ ᴄᴏɴsᴇʀᴠᴀᴛɪᴏɴ ᴏғ ᴍᴏᴍᴇɴᴛᴜᴍ ɪs ᴅᴇғɪɴᴇᴅ ᴀs ᴀ ᴘʀɪɴᴄɪᴘʟᴇ ɪɴ ᴘʜʏsɪᴄs ᴛʜᴀᴛ sᴛᴀᴛᴇs ᴛʜᴀᴛ ғᴇᴡ ᴘᴀʀᴛs ɪɴ ᴀɴ ɪsᴏʟᴀᴛᴇᴅ sʏsᴛᴇᴍ ʀᴇᴍᴀɪɴɪɴɢ sᴛᴇᴀᴅʏ ᴀɴᴅ ᴜɴᴄʜᴀɴɢɪɴɢ ᴏᴠᴇʀ ᴛɪᴍᴇ ᴇᴠᴇɴ ᴡʜᴇɴ ᴏᴛʜᴇʀs ᴀʀᴇ ᴍᴏᴠɪɴɢ.