The number of times that a wave vibrates in a unit of time is called
a. amplitude
b. frequency
c. wavelength
d. interference

Natural forces that can alter ecosystems include seasons and climate changes. t or f

Aknife blade is a(n) a. lever b. screw c. wedge d. inclined plane

Two pans of a balance are 24.1 cm apart. the fulcrum of the balance has been shifted 1.33 cm away from the center by a dishonest shopkeeper. by what percentage is the true weight of the goods being marked up by the shopkeeper? assume the balance has negligible mass. answer in units of %.