Answer
(a) $v=23.1mph$
(b) $v=22.2mph$
Work Step by Step
(a) We can find the speed as
$v=\frac{s}{t}$
we plug in the known values to obtain:
$v=\frac{100m}{9.69s}$.....eq(1)
But $1m=\frac{1}{1609.34}$miles
and $1 s=\frac{1}{3600}$hours
We plug in these values in equation (1) to obtain:
$v=\frac{100\times \frac{1}{1609.34}}{9.69\times \frac{1}{3600}}$
$v=23.1mph$
(b) $v=\frac{100yards}{9.21s}$.....eq(2)
We know that
$1 yard=\frac{1}{1760}$miles
and $1s=\frac{1}{3600}$hours
We plug in the known values in equation(2) to obtain:
$v=\frac{100\times \frac{1}{1760}}{9.21\times \frac{1}{3600}}$
$v=22.2mph$
