Knowledge Point 01: The Second Hand of a Quartz Clock Often Stops at the “9” Mark When the Battery Dies
When a quartz clock stops working due to a depleted battery, the second hand often stops at the “9” mark. This is because the gravitational torque acting on the second hand at this position is relatively large, hindering its movement.
Detailed Explanation:
During its movement, the second hand of a quartz clock is influenced not only by the driving torque but also by the gravitational torque. When the battery is depleted and the driving torque diminishes, the second hand gradually halts due to the effect of gravitational torque.
Since the angle between the second hand and the direction of gravity at the “9” position is relatively acute, the gravitational torque acting upon it is greater, making it prone to stopping at this spot. This occurrence exemplifies the impact of torque on an object’s motion state and serves as an illustrative instance of the torque principle in physics.
Knowledge Point 02: The Influence of Gravitational Torque on Object Motion
Gravitational torque is the product of gravity and the lever arm, illustrating the rotational impact of gravity on an object.
Detailed Explanation:
Gravitational torque is a pivotal concept in physics, elucidating how gravity influences an object’s rotational state. When an object is subjected to gravity, if a distance (lever arm) exists between its center of mass and the point of support, a gravitational torque arises.
The magnitude of this torque is contingent upon the product of gravity and the lever arm, while its direction is perpendicular to the plane encompassing the lever arm and gravity. The presence of gravitational torque can either impede or expedite an object’s rotation, thereby altering its motion state.
Knowledge Point 03: Brief Overview of the Working Principle of a Quartz Clock
A quartz clock harnesses the piezoelectric effect of a quartz crystal to produce a stable oscillation frequency, which subsequently powers the pointers to move and display the time.
Detailed Explanation:
A quartz clock is a precise timing device whose operational foundation rests on the piezoelectric effect of a quartz crystal. When a quartz crystal undergoes an external force, it undergoes a change in charge distribution, resulting in an electric potential difference. This potential difference, when subjected to an alternating voltage, prompts the quartz crystal to generate a stable oscillation frequency.
A quartz clock utilizes this frequency as a temporal benchmark and, through circuit processing, drives the pointers to move, thereby accurately displaying the time. The precision and stability of quartz clocks render them an indispensable timing tool in contemporary life.
