Answer
(a) $2.7N$
(b) $3.78N$
Work Step by Step
(a) We can find the change in the apple's momentum per second as follows:
$\frac{\Delta P}{\Delta t}=F$
$\frac{\Delta P}{\Delta t}=mg$
We plug in the known values to obtain:
$\frac{\Delta P}{\Delta t}=2.7N$
(b) We can find the required change in momentum as follows:
$\Delta P=F\Delta t$
We plug in the known values to obtain:
$\Delta P=(2.7N)(1.4s)$
$\Delta P=3.78N$