Which scientist formed his ideas about living things by performing observations without using a microscope? a) hooke b) malpighi c) van leeuwenhoek d) vesalius

Polly is pushing a box across the floor with a force of 30 n. the force of gravity is –8 n, and the normal force is 8 n. which value could describe the force of friction if polly could not move the box?

Sound is a disturbance that travels through a medium as a

Which of the following is the main energy source for the sun? a. fission of hydrogen b. fusion of hydrogen c. fusion of helium d. fission of iron