xét một cái hộp trượt có ma sát trên bề mặt nằm ngang nếu hệ là cái hộp và bề mặt nằm ngang thì hệ là

I'm having some difficulty seeing the diagram clearly.but the question says there's a net inward force on the object.so we know right away,  from newton's 2nd law of motion, thatthat baby is accelerating.  it doesn't even matter which way thenet force is pointing.  if there's any net force, then either theobject's speed or else its direction must be changing.

A=v^2/r solve for r hope that