The number of cycles a wave completes in an amount of time. 

A device that measures the presence of radiation and clicks a lot. 

In space no-one can hear you scream.    Why not? 

This type of motion involves an object moving back and forth repeatedly. 

What kind of motion has acceleration only due to gravity?      

This says that acceleration is proportional to the net force acting on an object, and that the constant of proportionality is the mass of the object.    ie:    F = ma

A weak link intentionally placed into an electric circuit. 

A vector has horizontal and vertical _____________________________. 

Objects in motion tend to stay in motion, unchanged, unless acted upon by an external force. Also, objects at rest tend to stay at rest unless acted upon by an external force. 

This is a property of matter that is influenced by mass. It is the ability of an object to resist changes to its motion.