If the half-life of a decaying isotope is 10 years, which statement is true after 10 years? A. there are more parent nuclei than daughter nuclei in a sample
B. The relative numbers of atoms cannot be determined
C. There are more daughter nuclei than parent nuclei in a sample
D. The numbers of parent nuclei and daughter nuclei in a sample are equal

Match the words or actions and their definition. 1. the rate of doing work 2. a machine that changes motion 3. the force that is used to generate electricity 4. 550 foot-pounds per second 5. the force that makes things fall toward the earth 6. work in > work out 7. metric measurement of work 8. the product of force times distance water falling from a dam newton-meter gravity work windmill power the work principle 1 horsepower