A starship voyages to a distant planet 10 ly away. The explorers stay 1 year, return at the same speed, and arrive back on earth 26 years, as measured on earth, after they left. Assume that the time needed to accelerate and decelerate is negligible. a. What is the speed of the starship? b. How much time has elapsed on the astronauts chronometers

PHYS 2010- Chapter 4 Notes What Is Force Definition: A force is something that is changes or tends to the state of rest or motion of an object. Force is not a thing on its own, its arises from interactions between objects. A force is avector. Described by a magnitude and a direction All vector rules apply. SI Unit of force: Newton, symbol N. Forces – Agent & Object A force is a push or a pull. Other examples: lifting, pressing, twisting, stretching…etc Force is a vector, it has magnitude and direction. Hence, we can draw vector diagrams for force. Combining Forces Net Force: Combination of all forces acting on 1 object at one time. Net force may be balanced or unbalanced. When several forces are exerted on an object, they combine to form a net force equal to the vect