Need asap how do scientist use the doppler effect to understand the universe

a. to determine the ages of plants
b. to determine plant composition
c. to determine light brightness
d. to determine motion of objects

Which of the following is a testable hypothesis? a. if i brush my teeth, i will get fewer cavities than if i don't brush my teeth. b. green toothpaste tastes better than blue toothpaste or red toothpaste. c. smart, careful, healthy people always brush their teeth. d. it's wrong to not brush your teeth before you have an important conversation with someone.

Which of the following are good traits of a hypothesis? it will be able to be testedit can predict an outcomeit will explain the observationsall of these

650.j is the same amount of energy as? 2720cal1550cal650.cal2.72cal