4-66 할리데이 11판 솔루션 일반물리학

$$\begin{cases} \vec v_3&=3.00\i+4.00\j\ut{m/s}\\ \vec v_5&=-3.00\i-4.00\j\ut{m/s}\\ \end{cases}$$ $$\ab{a}$$ $$\begin{aligned} \frac{T}{2}&=2\ut{s},\\ T&=4\ut{s} \end{aligned}$$ $$\begin{aligned} v&=\sqrt{3^2+4^2}\ut{m/s}\\ &=5\ut{m/s}\\ \end{aligned}$$ $$\begin{aligned} v&=\frac{2\pi R}{T},\\ R&=\frac{vT}{2\pi}\\ &=\frac{10}{\pi}\ut{m} \end{aligned}$$ $$\begin{aligned} a&=\frac{v^2}{R}\\ &=\frac{5^2}{\frac{10}{\pi}}\ut{m/s^2}\\ &=\frac{5\pi}{2}\ut{m/s^2}\\ \end{aligned}$$ $$\ab{b}$$ $$\begin{aligned} \vec a&=\frac{\Delta \vec v}{\Delta t}\\ &=\frac{\vec v_5-\vec v_3}{5-3}\\ &=\frac{(-3.00\i-4.00\j)-(3.00\i+4.00\j)}{2}\ut{m/s^2}\\ &=-3.00\i-4.00\j\ut{m/s^2}\\ \end{aligned}$$