In Physics terms, what is the difference between "speed" and "velocity"? (it is the same thing that differentiates "distance" from "displacement")

Which is not a source of noise pollution? a)airplanes b)acid rain c)machines d)cars

Two technicians are discussing a resistance measurement between the can-h and can-l wires. technician a says this measurement should be done with the ignition switch in the "run" position. technician b states that a measurement of 0 ohms indicates an open in the network. which technician is correct?

Which accurately compares concave and convex lenses?