Abstract: An inertial switch includes an open-ended outer casing formed of electrically conductive material. An insulated end cap is engageable with the open end of the outer casing to enclose the outer casing. An electrically conductive pin extends through the end cap and into the casing and is electrically isolated from the outer casing by the end cap. A longitudinally extending helical coil spring is secured to the pin adjacent one end thereof. The spring is electrically isolated from the outer casing but is deflectable about a longitudinal axis thereof to contact the outer casing thereby to close the inertial switch in response to accelerations of the inertial switch.

Abstract: A speed-sensing projectile such as for example a baseball includes a generally spherical body. An inertial switch is positioned within the body and is actuable between open and closed conditions in response to accelerations of the body greater than a threshold value. A processor also within the body is responsive to the inertial switch and calculates the average speed at which the baseball is thrown over a fixed distance. A visible display on the body is in communication with the processor and displays the calculated speed.

Abstract: An inertial switch includes an open-ended outer casing formed of electrically conductive material. An insulated end cap is engageable with the open end of the outer casing to enclose the outer casing. An electrically conductive pin extends through the end cap and into the casing and is electrically isolated from the outer casing by the end cap. A longitudinally extending helical coil spring is secured to the pin adjacent one end thereof. The spring is electrically isolated from the outer casing but is deflectable about a longitudinal axis thereof to contact the outer casing thereby to close the inertial switch in response to accelerations of the inertial switch.

Abstract: A speed-sensing projectile such as for example a baseball includes a generally spherical body. An inertial switch is positioned within the body and is actuable between open and closed conditions in response to accelerations of the body greater than a threshold value. A processor also within the body is responsive to the inertial switch and calculates the average speed at which the baseball is thrown over a fixed distance. A visible display on the body is in communication with the processor and displays the calculated speed.