When a machine is used to perform a task, work output is always more than work input. select the best answer from the choices provided t f?

What property is a characteristic of a substance that can be observed and does not change the identity of the substance

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.

Phase changes are chemical changes. true or false