Un trabajador de una construcción sube con velocidad constante un cuerpo de 20 kg de masa hasta una altura de 3 m, empleando un tiempo de 10 s en esta actividad. a) ¿Cuál es el valor de la fuerza F Que el trabajador debe ejercer para que el cuerpo suba con velocidad constante?considerar g= 10 m/s2

b) ¿Cuál es el trabajo mecánico que el trabajador realiza en esta operación?

c) ¿Cuál es la potencia que desarrolla el trabajador?

True or false when elements combine to form a mixture, the resulting chemical properties may be very different from those of the elements that make it.

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.

Which of the following is the phase that results when the moon is on the opposite side of the earth from the sun? a. quarter moon b. crescent moon c. new moon d. full moon