Question

Tim goes on a car journey.

for the first 15 minutes his average speed is 40 mph

he then stops for 25 minutes
he then completes the journey at an average speed of 45mph
the total journey time is 1 hour.
A) draw a distance time graph for his journey?
B) what is the average speed for the whole journey?

Answer 1

See attached picture ;

25 miles / hour

Explanation:

First phase :

Travel time = 15 minutes

Average speed = 40 mph

Distance covered = speed * time

Distance covered = 40 * (15/60) = 10 miles

Second phase :

25 minutes stop

Third phase :

Average speed = 40 mph

Distance covered = speed * time

Travel time = 60 - (25 + 15) = 20 minutes

Distance covered = 45 * (20/60) = 15 miles

Average speed for the journey :

Total distance / total time taken

= (10 miles + 15 miles) / 1 hour

= 25 miles / hour