I don't know how to do this question. A diagram would really help, but an explanation without one would also be fine :-)
A girl, of mass 40kg, is travelling in a lift holding a parcel by means of a light, inextensible string. The lift is travelling upwards and decelerating at 3ms-2, and the contact force exerted by the girl on the floor of the lift is 294N. Find the mass of the parcel.
Should I still go?