A family takes a trip from Philadelphia, PA to Washington, D. C. The trip takes 2 hours. They traveled the first hour at 40 km/h and the second hour at 80 km/h. What is their average speed during this trip?

Anonzero net force acts on a particle and does work. which one of the following statements is true? the kinetic energy of the particle changes, but the speed of the particle does not change. the kinetic energy of the particle does not change, but the speed of the particle does change. the kinetic energy of the particle changes, but the velocity of the particle does not change. the kinetic energy and the speed of the particle change, but the velocity of the particle does not change. the kinetic energy, speed, and velocity of the particle change.