When the forward and reverse paths of a change occur at the same rate,
a. the system is conserved.
b. the system is in equilibrium.
c. the change must be physical.
d. the change must be chemical.

A26 cm object is 18 cm in front of a plane mirror. a ray of light strikes the object and is reflected off the mirror at a 42-degree angle. what is the angle of reflection? degrees what type of image is formed? what is the size of the image? cm

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

The ability to make things happen is also called a. heat b. force c. matter d. energy