Consider a vehicle trying to pull another vehicle with a rope (PI: Vehicle in Tow). One of the vehicles is stuck in mud. What are the components (parts) of the system that influence its motion?
(two vehicles, the rope connecting them, the ground/mud, and the planet Earth [the source of gravity])

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.