Answer
a) $19.7\ km/h$
b) $547\ cm/s$
c) $4\ min:34\ s$
Work Step by Step
a) Calculate the average velocity in mi/min:
$v=\frac{\Delta s}{\Delta t}$
$v=\frac{1\ mi}{4.90\ min}=0.204\ mi/min$
Convert this velocity to km/h:
$0.204\ \frac{mi}{min}\cdot\frac{1.609\ km}{1\ mi}\cdot \frac{60\ min}{1\ h}=19.7\ km/h$
b) Convert the velocity from km/h to cm/s:
$19.7\ \frac{km}{h}\cdot \frac{10^3\ m}{1\ km}\cdot\frac{10^2\ cm}{1\ m}\cdot \frac{1\ h}{60\ min}\cdot\frac{1\ min}{60\ s}=547\ cm/s$
c) First, convert the velocity to m/s:
$547\ \frac{cm}{s}\cdot\frac{1\ m}{10^2\ cm}=5.47\ m/s$
Calculate the time required to cover a distance of 1500 m with this velocity:
$v=\frac{\Delta s}{\Delta t}$
$\Delta t=\frac{1500\ m}{5.47\ m/s}$
$\Delta t=274\ s$
Convert the time to min:
$274\ s\cdot\frac{1\ min}{60\ s}=4.57\ min$
The minutes part of the time is 4 min, to get the seconds part, convert the fractional part of this time to s:
$0.57\ min\cdot\frac{60\ s}{1\ min}=34\ s$
The time in the format minutes:seconds is:
$4\ min:34\ s$
