Physics - Mechanics - Newton's Laws - Free body diagrams - How Many Forces?

Show 6 scenarios and ask 'How many forces act on the object?' (1) A book on a table (2 - weight down, normal force up). (2) A ball in mid-air (1 - weight only, ignore air resistance). (3) A box being pushed across a floor (4 - weight, normal, push, friction). (4) A skydiver at terminal velocity (2 -