Ollie Okensfrei is playing hide-and-seek with his niece, Clara, in the backyard. Clara is making a dash for home base. By observing the path that she cuts across the grass Ollie finds that Clara's velocity is v→=(0.8ms−0.05ms3t2)i^+(2.1ms2t)j^ . What are the magnitude and direction of her acceleration at t=3s ? Assume that the positive x-direction is east and the positive y-direction is north.
a. a=2.12m/s2;θ=81.87∘ north of west
b. a=7.82m/s2;θ=19.4∘ south of east
c. a=3.38m/s2;θ=0.15∘ south of east
d. a=2.41m/s2;θ=8.13∘ north of west