솔루션피아

$$ \begin{cases} d&=35.0\ut{cm}\\ F_1&=5.00\ut{N}\\ F_2&=1.00\ut{N}\\ F_3&=6.00\ut{N}\\ \theta&=60.0\degree\\ m&=2.4\ut{kg}\\ K_0&=0 \end{cases} $$ $$\ab{a}$$ $$\Sigma \vec F = 0 \Harr \Delta \vec v=0,$$ $$\Sigma F_y=0$$ $$ \begin{aligned} \Sigma F_x &= F_1-F_2+F_3\cos\theta\\ &=7\ut{N} \end{aligned} $$ $$ \begin{aligned} W&=\vec F \cdot \vec d,\\ &=\frac{49}{20}\ut{J}\\ &=2.45\ut{J}\\ \end{alig..

$$ \begin{cases} F&=2.0\ut{N}\\ m&=4.0\ut{kg}\\ \Delta d_x&=+1.0\ut{m} \end{cases} $$ $$ \begin{aligned} \Delta K&= W=\vec F \cdot \vec d\\ &=Fd\cos\theta\\ \end{aligned} $$ $$\ab{a,b}$$ $$ \begin{aligned} K&=K_0+\Delta K\\ \frac{1}{2}m{v_f}^2&=\frac{1}{2}m{v_0}^2+Fd\cos\theta\\ \end{aligned} $$ $$ \begin{aligned} v_f&=\sqrt{{v_0}^2+\frac{2Fd\cos\theta}{m}}\\ &=\sqrt{{v_0}^2+\cos\theta} \end{ali..

$$ \begin{cases} A:\text{Time 0 to 1}\\ B:\text{Time 1 to 2}\\ C:\text{Time 2 to 3}\\ \end{cases} $$ $$ \begin{cases} v&=0.60\ut{m/s}\\ m&=3.5\ut{kg} \end{cases} $$ $$ \begin{cases} \theta_A&=10\degree\\ S_A&=4.2\ut{m}\\ \end{cases} $$ $$ \begin{cases} \theta_B&=0\\ S_B&=2.0\ut{m}\\ \end{cases} $$ $$ \begin{cases} \theta_C&=-10\degree\\ S_C&=4.2\ut{m}\\ \end{cases} $$ $$W=\vec F \cdot \vec d,$$ ..

$$ \begin{cases} \Delta x &= +5.0\ut{cm}\\ W_0&=30\ut{J} \end{cases} $$ $$W=\vec F \cdot \vec d,$$ $$ \begin{aligned} W(\phi)&=F d \cos \phi\\ W(0)&=F d\cos 0=30\ut{J}\\ \end{aligned} $$ $$ \therefore F d=30\ut{J} $$ $$ W(\phi)=30\cos \phi $$ $$\ab{a}$$ $$\phi=57\degree$$ $$ \begin{aligned} W(57\degree)&=30\cos 57\degree\ut{J}\\ &\approx 16.339171050450812\ut{J}\\ &\approx 16\ut{J}\\ \end{aligne..

$$ \begin{cases} B:\text{Box}\\ H:\text{Hand}\\ \end{cases} $$ $$ \begin{cases} m&=30.0\ut{kg}\\ g&=9.80665\ut{m/s^2}\\ \end{cases} $$ $$\ab{a}$$ $$\Sigma \vec F = 0 \Harr \Delta \vec v=0,$$ $$ \begin{aligned} \Sigma F_y&=2T-mg=0\\ T&=\frac{mg}{2}\\ &=15g\\ &=147.09975\ut{N}\\ &\approx 147\ut{N}\\ \end{aligned} $$ $$\ab{b}$$ $$ \begin{aligned} \Delta y_H&=2\Delta y_B\\ &=7.00\ut{cm} \end{aligned..