As Kath leaves Waco while driving her car to Austin she accelerates at a constant rate. If her speed increases

Question

from 30 mph to 75 mph in 22 sec, determine her acceleration in units of ft/sec/sec.
hint: 60 mph=88 ft/sec

Answer 1

difference in sped = 75 - 30 = 45 mph
1 mph = 22/15 ft /sec
45 mph = 45(22/15) = 66 ft/s
acceleration = change in velocity(speed) /change in time
= 66/22 = 3 ft/sec^2

Answer 2

acceleration = (75 - 30)/22 mph/sec = 45/22 mph/sec
and 15 mph = 22 ft/sec

so accleration = (3 * 22)/22 ft/sec/sec = 3 ft/sec/sec