Finally, we come to Jason Snell’s surprise at how light the 15 Pro seemed when he played with it in the hands-on area. He mentioned this not only in his Macworld article, but also in the post-keynote episode of Upgrade. You wouldn’t expect a change from 206 g for the 14 Pro to 187 g for the 15 Pro would be that noticeable, but Greg Joswiak mentioned it in the keynote and Jason confirmed it. How can that be?
One answer is that people are just more sensitive than we give them credit for being. A 9–10% drop in weight may seem like a small amount to our brains but a large amount to our hands. But because it allowed me to do some simple calculations, I decided to look into another possibility.
Your ability to manipulate a phone is based primarily on its mass, but also on its moment of inertia. And since the reduction in mass when switching from stainless steel to titanium is occurring almost entirely at the perimeter of the phone, the moment of inertia should be reduced more than if the mass were reduced uniformly.
Drang, of course, shows his work. There’s no doubt in my mind that there’s something to this: the new iPhones Pro feel even lighter than the weight reduction alone would suggest.