All Problems

Kinematics

Problem 1.56

A solid body rotates with angular velocity ω=ati+bt2j,\omega=a t \mathbf{i}+b t^{2} \mathbf{j}, where a=0.50rad/s2,b=0.060rad/s3,a=0.50 \mathrm{rad} / \mathrm{s}^{2}, b=0.060 \mathrm{rad} / \mathrm{s}^{3}, and i\mathbf{i} and j\mathbf{j} are the unit vectors of the xx and yy axes. Find: (a) the moduli of the angular velocity and the angular acceleration at the moment t=10.0 st=10.0 \mathrm{~s}; (b) the angle between the vectors of the angular velocity and the angular acceleration at that moment.

Reveal Answer
 (a) ω=at1+(bt/a)2=8rad/s,β=a1+(2bt/a)2==1.3rad/s2; (b) 17\text { (a) } \omega=a t \sqrt{1+(b t / a)^{2}}=8 \mathrm{rad} / \mathrm{s}, \beta=a \sqrt{1+(2 b t / a)^{2}}==1.3 \mathrm{rad} / \mathrm{s}^{2} ; \text { (b) } 17^{\circ}