161. A body of mass $4\,\text{kg}$ slides down a frictionless inclined surface that makes an angle $\alpha$ with the horizontal, with initial speed $4\,\dfrac{\text{m}}{\text{s}}$ upward along the surface. If the speed of the body reaches zero after $0.5\,\text{s}$, how large is the force (in Newtons) that the body exerts on the surface? $\left(g = 10\,\dfrac{\text{m}}{\text{s}^2}\right)$ $32\ (1$ $24\ (2$ $8\ (3$ $6\ (4$
\textbf{161.} A body of mass $4\,\text{kg}$ slides down a frictionless inclined surface that makes an angle $\alpha$ with the horizontal, with initial speed $4\,\dfrac{\text{m}}{\text{s}}$ upward along the surface. If the speed of the body reaches zero after $0.5\,\text{s}$, how large is the force (in Newtons) that the body exerts on the surface? $\left(g = 10\,\dfrac{\text{m}}{\text{s}^2}\right)$
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$32\ (1$ \hspace{2cm} $24\ (2$ \hspace{2cm} $8\ (3$ \hspace{2cm} $6\ (4$
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