The Physics of the Apple

Male figure dressed like Newton holding a red apple in the hand
October 2, 2020  TECHNOLOGY  


No fruit has achieved such fame in the world of physics as the humble apple. After all, it was an apple falling from a tree that inspired Isaac Newton’s law of gravity. Time to pay tribute to the physics of the apple!


However, we don’t really know what happened when the apple supposedly fell on Newton. Many artists have depicted the inspirational moment with the apple falling directly onto the head of the famous and eccentric scientist. In reality, it was probably less spectacular, but it was undoubtedly Newton’s ‘eureka‘.


So what do we know? The apple variety that inspired Isaac Newton was the Flower of Kent, a variety that is not cultivated commercially today, being more of a cooking apple, mealy with a subacid flavour. In short – it would not appeal to the palate of today. We have no idea what Newton’s opinion of it was. Incidentally, apples have been available in many varieties for a very long time. Even the Romans cultivated different apple varieties, and today it is estimated that there are more than 30,000 varieties of apple  worldwide. You can, however, still find a few Flower of Kent apple trees in some private gardens – including some universities that choose to remember Isaac Newton in this way.


The apple is, in many ways, a fascinating plant. We have collected some exciting data from HBK’s product physics domains.


Let’s start with the weight. On average, an apple weighs between 110 and 150 grams. But there’s more to it than that. In Japan, according to the Guinness Book of Records, the world’s largest apple was bred ten years ago – weighing in at an impressive 1.8 kg.


Moving on to acoustics. The loudest apple crunch in the world (when you bite into it) is the New Zealand variety Sweetango, reaching 79.1 dB. Sweetango ranks in a noise league alongside a doorbell or a kitchen mixer.


Think back to your schooldays, when we experimented with generating electricity from an apple? It is relatively easy to do this with apples or indeed other fruits. An apple generates a voltage of around 0.9 V.


So as you can see, the world of physics can be represented in an apple. And yet, some very important questions remain unanswered. For example, the one about the gravitational constant that occurs when falling. Read how Scientists are pursuing this gravitational constant with increasingly precise methods.


With all this in mind – maybe we should also sit under an apple tree once in a while and see what happens?

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