a hdd can take a lot of g forces before it breaks. the label should give a rating but i believe it is something like 100g's.
but if the hdd is reading/writing data when you drop it or shake it a lot, it can mess it up. the quick jerking can cause the laser head to bump into the spinning disk inside the drive. this can scratch the disks and cause issues. years ago i had one of those 60 gb ipods before they went all flash memory. it had a spinning hdd. after a couple months using it while running on a treadmill it starting having issues. lost data and a scrapping sound i could hear at times. the jerking motion caused by my running with it (had it in one of those arm bands you can buy to hold ipods/phones) managed to both scratch the...