5-51 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} m_1&=4.00\ut{kg}\\ m_2&=3.00\ut{kg}\\ \theta_1&=25.0\degree\\ \theta_2&=65.0\degree\\ \end{cases} $$ $$\Sigma \vec F = m\vec a,$$ $$ \begin{cases} \Sigma F_1 &= m_1 a\\ \Sigma F_2 &= m_2 a\\ \end{cases} $$ $$ \begin{cases} T-m_1g\sin\theta_1 &= m_1 a\\ m_2g\sin\theta_2-T &= m_2 a\\ \end{cases} $$ $$ \begin{aligned} T &= \frac{ m_1 m_2 }{m_1+m_2}g\br{\sin\theta_1+\sin\theta_2}\\ &={12\over7}\br{\cos25\degree+7\sin25\degree}g\\ &\approx 22.34110737641553\ut{N}\\ &\approx 22.3\ut{N}\\ \end{aligned} $$