Question

When the legal speed limit for the New York Thruway was increased from 55 mi/h to 65 mi/h,

how much time was saved by a motorist who drove the 700 km between the Buffalo entrance and
the New York City exit at the legal speed limit?

Answer 1

`\Delta t = 1.22 hours`

Step-by-step explanation:

Initially legal speed to move through the drive way is 55 mi/h

so it is given as

`v_1 = 55 mph = 24.48 m/s`

final legal speed is given as

`v_2 = 65 mph = 28.93 m/s`

now we know that time taken to cover the distance of 700 km is given by the formula

`t = (d)/(v)`

so initially time taken to cover that distance is

`t_1 = (700 * 10^3 m)/(24.48 m/s)`

`t_1 = 28595 s = 7.94 h`

Now if legal speed is increased then the time taken to move through same distance is given as

`t_2 = (700 * 10^3)/(28.93)`

`t_2 = 24196 s = 6.72 h`

so total time saved is given as

`\Delta t = t_1 - t_2`

`\Delta t = 1.22 hours`