modern oil tankers weigh more than a half-million tons and have lengths of up to one-fourth mile. Such massive ships require a distance of 5.0 km (about 3.0 mi) and a time of 20 min to come to a stop from a top speed of 30 km/h.

Question

What is the magnitude of a such a ship's average acceleration in m/s^2 in coming to a stop?

what is the magnitude of the ships average velocity in m/s?

Deb · Accepted Answer

Where did you get 3600 seconds?

Damon · Answer

5000 meters in 20*60 = 1200 seconds

Vi = 30,000 m / 3600 s = 83.3 m/s

v = Vi + a t
0 = 83.3 + a (1200)
a = - .0694 = - 6.94 * 10^-2 m/s^2

average velocity with constant acceleration = (first + last)/2
= 83.3/2 = 41.7 m/s

Katie · Answer

why is it not 30-0/20=1.5 and 5/20=4 km/min = 4,000 m/min = 66.67 m/s?

Damon · Answer

5/20=4 km/min = 4,000 m/min = 66.67 m/s? BECAUSE 5/20 = 1/4 not 4

Deb · Answer

I figured it out. 3600 seconds in an hour.

matt · Answer

30,000 m / 3600 s = 8.333 m/s