Chapter 2 2.3 Time, Velocity, and Speed. 12. The speed of propagation of the action potential (an electrical signal) in a nerve cell depends (inversely) on the diameter of the axon (nerve fiber). If the nerve cell connecting the spinal cord to your feet is 1.1 m long, and the nerve impulse speed is 18 m/s, how long does it take for the nerve signal to travel this distance? 2.4 Acceleration 19. Assume that an intercontinental ballistic missile goes from rest to a suborbital speed of 6.50 km/s in 60.0 s (the actual speed and time are classified). What is its average acceleration in m/s and in multiples of g (9.80 m/s2) ? 2.5 Motion Equations for Constant Acceleration in One Dimension 25. At the end of a race, a runner decelerates from a velocity of 9.00 m/s at a rate of 2.00 m/s. (a) How far does she travel in the next 5.00 s? (b) What is her final velocity? (c) Evaluate the result. Does it make sense