Answer
(a) $12.0s$
(b) $55.5s$
Work Step by Step
(a) We can find the required time taken toward east as follows:
$1.75m/s cos18^{\circ}=(1.75m/s)(0.951)=1.664m/s$
Now $t=\frac{s}{v}$
We plug in the known values to obtain;
$t=\frac{20m}{1.664m/s}$
$t=12.0s$
(b) We can find the time taken toward north as
$(1.75m/s)sin18^{\circ}=(1.75m/s)(0.309)=0.541m/s$
Now $t=\frac{s}{v}$
We plug in the known values to obtain:
$t=\frac{30m}{0.541m/s}$
$t=55.5s$
