Scientists estimate that by the year 2013, the world's population will reach:

A. 1 billion

B. 6 billion

C. 7 billion

D. 10 billion

A heat engine is designed to do work. This is possible only if certain relationships between the heats and temperatures at the input and output hold true.

A TV with a power rating of 400 W uses 0.6 kWh in one day. For how many hours was the TV on during this day? Round answer to the tenths and include the unit.

Why does a rocket have such great momentum even if it is moving at a slow speed?

Which of the following describes sound waves? A. Mechanical waves in which the vibrations are perpendicular to the motion of the sound B. Electromagnetic waves in which the vibrations are parallel to the motion of the sound C.

Look at the densities of the jovian planets given in figure 1. which of the following statements best describes the pattern of jovian planet densities?

What is the direction of the force when an object moved in a circle

An observer notes that the pitch of a sound is becoming progressively higher. the observer can conclude that the sound is moving

A falling back in mid air has what

What objects are often arranged by their properties

Which nuclei is not radioactive? A. Am-241 B. Mg-24 C. Pu-241 D. U-238