I need help with question A

Apulley system lifts a 500-ib block 1.0 foot with an effort of only 50 ib. if the 50 ib moves 30 feet, calculate the efficiency of the pulley system. a. 30% b. 33% c. 70% d. 67%

What are chlorofluorocarbons and what impact do they have on the atmosphere?

Power can be defined as a. the distance over which work was done. b. how much work can be done in a given time. c. all the work in an given area. d. the energy required to do work.