Which criterion did this sleep cycle alarm clock fail to meet?
Humans sleep in cycles, usually two or three cycles per
night. There is a point in each cycle when waking up will
leave the sleeper feeling the most rested and refreshed.
After learning about this, a computer programmer
designed a new smartphone alarm clock. This new
alarm clock uses sensors in the smartphone to detect
the sleeper's motion and determine when the sleeper
has reached the best point in the sleep cycle at which to
wake up. The app can be downloaded onto any
smartphone. Most users who download this app find that
it does not help them wake up feeling more refreshed,
but they are willing to try improved products in the future.
It did not solve the problem.
It was not cost effective enough.
It was not readily available.
It was not safe for most users.

Achemical reaction (also known as a chemical change) produces substances that are chemically different from the starting materials. an example of a chemical reaction is the formation of water from hydrogen and oxygen gas. in a physical change, a substance changes its physical appearance but not its chemical identity. an example of physical change is the formation of liquid water from solid water, a familiar process called melting. physically, liquid water looks very different from solid water (ice) but the chemical identity, water, is the same for both. which of following changes that affect the composition of our atmosphere involve physical changes and which involve chemical reactions? oxygen gas changes to ozone during thunderstorms carbon dioxide is produced by the combustion of gasoline in an automobile engine. when coal, oil, and natural gas are decomposed in landsills they produce methane gas. freezing rain develops when a warm air mass overrides a cold air mass. fog forms from water vapor when the temperature drops below the dew point

What is the standard unit of measure for acceleration?

How is the atomic number of a nucleus changed by alpha decay