Answer to Question #299832 in Mechanics | Relativity for Katrina

Question

you normally drive on the freeway between butuan city and cagayan de oro city at an average speed of 100km/hr (62.14 mi/hr), and the trip takes 4 hours and 30 mins on a friday afternoon, however, heavy traffic slows you down and you drive the same distance at an average speed of only 70km/hr (43 mi/hr). how much longer does the trip take?

Answer 1

For the case of a normal trip, we determine the distance between cities

We have

$v=100km/hr$

$t= 4hr30mins=4.5 hr$

then the distance between cities is

$S=v \cdot t=100 \cdot 4.5 = 450km$

then for the average speed

$u=70 km/hr$

travel time is

$\tau=\frac{S}{u}=\frac{450}{70}=6.43hr=6hr25mins48sec$