On what part of the axis graph is the independent variable located

Atransverse wave is traveling on a string stretched along the horizontal x-axis. the equation for the vertical displacement y of the string is given by y = (1.8 x 10-3)cos[π(13x - 60t)], where all quantities are in si units. what is the maximum speed of a particle of the string

Which simple machine is not part of this compound machine? a. lever b. pulley c. inclined plane d. wheel and axle

Name three different units of energy used to measure heat and describe what type of situations each is usually used.