I need help with a lab 5 homework ​

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

In an experiment, how can i change human errors? be specific.

Four objects each with charge +2.0×10−7c are located at the corners of a square whose sides are 2.0 m long. part a what quantities can be determined using this information? check all that apply. the electric force on a charged object placed at the center of the square. the mass of each object. the total electric potential energy of the system consisting of the four charged objects. part b find the electric force on a charged object placed at the center of the square.