Q. Suppose that you hear a clap of thunder 18.4 s after seeing the associated lightning stroke. The speed of sound waves in air is 343 m/s and the speed of light in air is 3.00 108 m/s. How far are you from the lightning stroke?
Q. A factory worker pushes a 28.4 kg crate a distance of 4.5m along a level floor at constant velocity by pushing downward at an angle of 28 degree below the horizontal. The coefficient of kinetic friction between the crate and floor is 0.25.