A car is traveling at 20 meters/second and is brought to rest by applying brakes over a period of 4 seconds. What is its average acceleration over this time interval?

An unknown mineral sample has a mass of 318 g and a volume of 120 cm³. which mineral could the sample be? a. gypsum (density = 2.3 g/cm³) b. quartz (density = 2.65 g/cm³) c. apatite (density = 3.1 g/cm³) d. zircon (density = 4.65 g/cm³)