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

Answer:

$\Delta t = 1.22 hours$

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

$t = \frac{d}{v}$

so initially time taken to cover that distance is

$t_1 = \frac{700 \times 10^3 m}{24.48 m/s}$

$t_1 = 28595 s = 7.94 h$

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

$t_2 = \frac{700 \times 10^3}{28.93}$

$t_2 = 24196 s = 6.72 h$

so total time saved is given as

$\Delta t = t_1 - t_2$

$\Delta t = 1.22 hours$