Usted levanta un libro de física de10 N en el aire una distancia de 1.0 m, a una velocidad constante de 0.50 m / s. ¿Cuál es el trabajo realizado por la fuerza aplicada al libro?

Why is there friction between objects

You have been called to testify as an expert witness in a trial involving a head-on collision. car a weighs 1515 lb and was traveling eastward. car b weighs 1125 lb and was traveling westward at 44.0 mph. the cars locked bumpers and slid eastward with their wheels locked for 22.5 ft before stopping. you have measured the coefficient of kinetic friction between the tires and the pavement to be 0.750 . how fast (in miles per hour) was car a traveling just before the collision? (this problem uses english units because they would be used in a u.s. legal proceeding.)

Select the word from the list that best fits the definition classification of most stars on the h-r diagram