Answer
(a) The average speed is 21.2 m/s
(b) The magnitude of the average velocity is 15.6 m/s
Work Step by Step
(a) The total distance when traveling from Killarney to Mallow and then to Cork is $39~km + 22~km$ which is $61~km$.
$average ~speed = \frac{distance}{time}$
$average ~speed = \frac{61~km}{48~min}$
$average ~speed = \frac{61,000~m}{(48)(60~s)}$
$average ~speed = 21.2~m/s$
(b) We can find the magnitude of the displacement:
$\sqrt{(39~km)^2+(22~km)^2} = 44.8~km$
$average~velocity = \frac{displacement}{time}$
$average ~velocity= \frac{44,800~m}{(48)(60~s)}$
$average ~velocity= 15.6~m/s$
The magnitude of the average velocity is 15.6 m/s
