A mass is positioned on a frictionless slope that makes an angle of $30^\circ$ with the horizontal. It is then let go. What is its acceleration down the slope?
- A$4.9\,\text{m s}^{-2}$
- B$5.7\,\text{m s}^{-2}$
- C$8.5\,\text{m s}^{-2}$
- D$9.8\,\text{m s}^{-2}$