A pulley system lifts a 500-lb. block 2.0 feet with an effort of only 50 lb. If the 50 lb. moves 30 feet, calculate the efficiency of the pulley system.

Which of the following facts about electromagnetic radiation has made it possible for scientists to gather information about Venus' rocky surface? A. Ultraviolet rays have wavelengths that are too short to be seen with the unaided eye. B.

What is the correct reference frame for a given situation?

What is the name for the force that pushes electrons along in a circuit?

1 - Don't put the coat on the snowman - it will melt him 2 - I don't think the coat will make any difference 3 - I think it will keep him cold and stop him from melting.

Two bumper cars move in a straight line with the following equations of motion: x1 = - 4.0 m + (1.1 m/s) t x2 = 8.8 m + (-2.9 m/s) t what time do they collide?

Which of the following statements are true? a. A satellite's motion is independent of its mass. b. A satellite's velocity and orbital radius are independent of each other. c. A geosynchronous satellite has a period of approximately 28 days. d.

Latent heat of vaporization refers to which changes of state? liquid to gas or gas to liquid solid to gas or gas to solid solid to liquid or gas to liquid gas to liquid or liquid to solid

In what part of the scientific method do you record data? a. Conclusion b. Experiment c. Analysis d. Hypothesis

What is the basic definition of a black hole? a. any compact mass that emits no light b. a dead star that has faded from view any object from which the escape velocity exceeds c. the speed of light any object made from dark matter d.

A system uses 2380 I of energy to do work as 12,900 j of heat are added to the system. The change in internal energy of the system is