As part of your office network you want store backup data on usb drives. theoretically, what is the maximum number of usb drives that you can connect to a usb hub?

i think it is a female.

only #2 represents an object at rest on a table.

in #1, there is no normal force due to the table; the object is accelerating downward.

in #3, the vertical forces are not balanced; the object is accelerating downward.

in #4, neither the vertical nor the horizontal forces are balanced. the object is accelerating upwards and to the right.