Which of the following measures movement but does not indicate position?

A tachometer is an instrument that measures the rotational speed of a shaft or disc in a motor or other machinery, typically expressed in revolutions per minute (RPM). It provides data about how fast something is moving, making it useful in applications where speed measurement is critical. However, it does not provide information about the position of the component being measured, such as where it is located along its path of movement.

In contrast, contact and non-contact limit switches are designed specifically to determine if an object has reached a certain position or limit within a system. A linear transducer, on the other hand, directly measures the position of an object or component along a line, providing precise location information. Hence, these options are focused on positional feedback rather than speed. The tachometer stands out because its primary function is speed measurement without any reference to specific location.