The value of the action potential -- how much greater the electric potential is inside the axon as compared to outside the axon -- is around 30 mV for the average neuron in humans. If the length constant of an axon is about 2 mm, at what distance LaTeX: xx (to the nearest tenth of a mm) from the end of the axon where this action potential is applied would the potential difference across the membrane become less than 1.6 mV (which is a very weak signal)

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.