PLEASE HELP FAST!! What makes a model not useful? a)if it is in proportion with the object it represents
b)if it is made of a different material than the object it represents
c)if it is not the same mass of the object it represents
d)if it is out of proportion with the object it represents

In the sport of parasailing, a person is attached to a rope being pulled by a boat while hanging from a parachute-like sail. a rider is towed at a constant speed by a rope that is at an angle of 15 ∘ from horizontal. the tension in the rope is 1900 n. the force of the sail on the rider is 30∘ from horizontal. what is the weight of the rider? express your answer with the appropriate units.

Two objects of different mass start from rest, are pulled by the same magnitude net force, and are moved through the same distance. the work done on object 1 is 900 j. after the force has pulled each object, object 1 moves twice as fast as object 2. how much work is done on object 2?

What is similar between metals and suspensions