Does "the motor speed" mean the speed of the motor? [closed]

If you are wondering why we don't say 'the motor's speed', it is just that idiomatically, with very specific things we simply drop the apostrophe s.

Doctor's and nurses will talk about their patients' 'heart rate', 'pulse rate', 'breathing rate', 'blood count', 'flesh tone'. We talk about having 'kidney trouble', or 'liver trouble'.

When driving a car we will watch out for the 'speedometer reading'. We replace faulty 'headlight bulbs' etc.

In the garden we will use a 'hedge trimmer', 'garden shears' etc.

In none of these examples and scores more, where you might expect to find a possessive apostrophe, they are dropped and a 'compound noun' is formed. Some people might argue that such terms should be hyphenated.

"Motor speed" is likely used as a contrast to "land speed", "air speed", etc. A motor speed would likely be measured, for example, in RPM, whereas other relevant speeds could be measured in MPH, or some other measure.

For example, in a motor boat, the motor speed is not necessarily proportional to the "actual" speed of the boat (when accelerating, for example, there's some delay between throttling up and actual acceleration).