The French press is a popular device for brewing coffee, comprising a cylindrical beaker—or “jug”—fitted with a lid and plunger with a fine wire mesh filter. The plunger is used to drive the solid coffee particles to the bottom of the jug, separating these grounds from hot liquid above. When using the French press in this way, a growing permeable pack of ground coffee is pushed through hot water by applying force to the plunger. We use a combination of kitchen-based and laboratory experiments to determine the force required to push on the plunger as a function of the speed of the plunger and the mass of coffee used. We calculate that for the recommended preparation method, the maximum force is $32$ N to complete the pressing action in 50 s. We propose that home coffee preparation provides a fun, low-cost, and relatable learning opportunity for students and for those who are interested in coffee science.

中文翻译：

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在法式压力机上操作柱塞所需的力

法压壶是一种流行的咖啡冲泡设备，它包括一个圆柱形烧杯——或“壶”——装有盖子和带有细丝网过滤器的柱塞。柱塞用于将固体咖啡颗粒驱动到壶底部，将这些咖啡渣与上方的热液体分离。以这种方式使用法式压滤机时，通过对柱塞施加压力，将不断增长的可渗透咖啡粉包推入热水中。我们结合基于厨房和实验室的实验来确定推动柱塞所需的力，作为柱塞速度和所用咖啡质量的函数。我们计算出对于推荐的制备方法，最大力为$32$N 在 50 秒内完成按压动作。我们建议家庭咖啡准备为学生和对咖啡科学感兴趣的人提供有趣、低成本和相关的学习机会。