7. find the direction and magnitude of the vectors
a. x=(5.0 m) î + (-2.0 m) î
b. b=(-2.0 m) î + (5.0 m) ſ and
c. åt b
8. find the direction and magnitude of the vectors
a. a = (25 m) î + (-12.0 m) ſ

Suppose that 27 j of work is needed to stretch a spring from its natural length of 6 m to a length of 9 m. (a) how much work is needed to stretch the spring from 12 m to 14 m? j (b) how far beyond its natural length will a force of 78 n keep the spring stretched?

Which best term to describe a chemical reaction that absorbs energy from its surroundings? a. thermal conductor b. thermal insulator c. endothermic d. exothermic

Which of these activities increases the amount of carbon in the atmosphere?