if you push a wooden crate across rough ground with a force F over a distance d. a constant frictional force of magnitude f acts opposite in direction to the displacement what is the potential energy stored in the system due to these forces

Arunner is training for an upcoming marathon by running around a 100-m-diameter circular track at constant speed. let a coordinate system have its origin at the center of the circle with the x-axis pointing east and the y-axis north. the runner starts at (x, y) = (50 m, 0 m) and runs 2.5 times around the track in a clockwise direction.