大小分别为 $60\,\mathrm{N}$、$20\,\mathrm{N}$、$16\,\mathrm{N}$ 和 $14\,\mathrm{N}$ 的共面力沿图示方向作用于同一点。

求合力的大小和方向。

Answer all questions. You should use a calculator where appropriate.

You must show all necessary working clearly; no marks will be given for unsupported answers from a calculator.

Give non-exact numerical answers correct to 3 significant figures, or 1 decimal place for angles in degrees, unless a different level of accuracy is specified in the question.

请回答所有题目。适当时应使用计算器。必须清楚展示所有必要的计算过程；仅给出计算器答案而没有过程，不予评分。除非题目另有精度要求，非精确数值答案保留 3 位有效数字，以度为单位的角度保留 1 位小数。

Where a numerical value for the acceleration due to gravity ($g$) is needed, use $10\,\mathrm{m\,s^{-2}}$.

需要使用重力加速度 $g$ 的数值时，取 $10\,\mathrm{m\,s^{-2}}$。

取右和上为正方向，分别合成水平、竖直分量。合力向左上方，必须结合象限说明角度。

Taking rightwards and upwards as positive, the components of the resultant are

Thus the magnitude is

Since $R_x<0$ and $R_y>0$, the resultant acts upwards and to the left. Its angle $\theta$ above the leftward horizontal satisfies

Hence its direction is $\boxed{64.8^\circ\text{ above the }14\,\mathrm{N}\text{ force}}$, equivalently $25.2^\circ$ to the left of the upward vertical.