If a car travels 200 km at an average velocity of 40 km/hr, and a second car starting 1.0 hour later arrives at the 200 km destination at the same time, what is the average speed of the second car?

Mar 27, 2016

The average speed of the second car is $50 \text{km"/"h}$

Explanation:

For the first car we have,

Distance: 200 km
Average speed: 40 km/hr
Start Time: Let's say 12:00 pm, noon
Stop Time: $\frac{200}{40} = 5 \text{ hrs}$, which is 5:00 pm

For the second car, we have,

Distance: 200 km (same distance)
Average speed: ? This is what we want to know
Start Time: 1:00 pm
Stop Time: 5:00 pm (same time)

Because $\text{Distance" = "Rate"xx"Time}$, we have

200 km = $R \times 4 \text{ hrs}$ (time between 1:00 pm and 5:00 pm)
R=(200 " km")/(4 " hrs") = 50 "km"/"h"