Answer
(a) $N=128N$
(b) $F=69N$
Work Step by Step
(a) We can find the normal force as
$N=\frac{mg}{1+\mu_ktan\theta}$
We plug in the known values to obtain:
$N=\frac{(18)(9.81)}{1+(0.38)(tan45^{\circ})}$
$N=128N$
(b) We can find the required tension force as
$F=\frac{\mu_kN}{cos\theta}$
We plug in the known values to obtain:
$F=\frac{(0.38)(128)}{cos45^{\circ}}$
$F=69N$
