A treadmill is provided according to various embodiments herein. The treadmill includes a frame; a front shaft coupled to the frame; a rear shaft coupled to the frame; and a running belt disposed about the front and rear shafts, wherein the running belt assumes at least a portion of a curved running surface, the curved running surface having a radius of curvature of approximately 88 to 138 inches.

Golf balls including one or more layers having at least one radar detectable mark disposed on the surface thereof are provided.

Golf balls including one or more layers having at least one radar detectable mark disposed on the surface thereof are provided.

Golf balls including one or more layers having at least one radar detectable mark disposed on the surface thereof are provided.

Golf balls including one or more layers having at least one radar detectable mark disposed on the surface thereof are provided.

An exercise machine is disclosed. The exercise machine comprises a pancake motor. The exercise machine comprises a torque controller coupled to the pancake motor. The exercise machine comprises a high resolution encoder coupled to the pancake motor.

Provided is an electronic device including: a trajectory calculation unit measuring an initial physical quantity of a hit ball and calculating a trajectory of the ball by using the initial physical quantity; an azimuth sensor measuring a first azimuth corresponding to a direction that the trajectory calculation unit faces; and a control unit calculating a displacement of the ball by using the first azimuth and the trajectory of the ball.

A golf ball is disclosed herein that includes at least one radar detectable mark such that a projected pattern is formed when the at least one radar detectable mark is radially projected onto an outer surface of the golf ball. The projected pattern can have a first wave profile mapped along a path defined by a first spherical arc on the outer surface of the golf ball. The projected pattern can comprise at least one first crest and at least one first trough. The projected pattern can have a periodic function selected from: a sine wave, a sawtooth wave, a triangle wave, or a square wave.

An exercise machine is disclosed. The exercise machine comprises a motor, an actuator, an arm, and a cable. The cable is coupled between the motor and the actuator through the arm. The motor is configured to provide a nominal tension of resistance when an end of the cable is within a range of length from a zero point associated with the cable.

A timing device is provided herein. The timing device includes a housing defining an aperture in a surface thereof. An elongated member is extendable from the housing. A wheel is attached to an interior surface of the housing. An encoder is operably coupled to the wheel and is configured to calculate a rotational velocity of the wheel. A controller is configured to calculate a linear velocity of the elongated member based on the rotational velocity of the wheel.