Solution

Engineering Mechanics (Dynamics)

Chapter 12

Exercise 229

−vr​j=−60i+vr/a​cos30∘i−vr/a​sin30∘j

$$\bigg(\frac{\sqrt{3}}{2}v_{r/a} - 60\bigg)\bold{i} + \bigg(v_r - \frac{1}{2}v_{r/a}\bigg) \bold{j}= 0$$

This requires, ~

$$\begin{align*} \frac{\sqrt{3}}{2}v_{r/a} - 60 &= 0 & v_r - \frac{1}{2}v_{r/a} &= 0\\ \end{align*}$$

Answer

vr​=34.64 km/h