The main issue is body composition (see the body fat calculator for more). Calorie expenditure will vary depending on the ratio of body fat to muscle or lean mass. NOTE that as our bodies adapt to exercise and our body composition changes - so will the amount of Calories burned.
The definition of a throttle is a valve that controls the fluid flow. An example of a throttle is a car part that controls how fuel moves through the system. Throttle is defined as to control the speed of an engine or the flow of fuel in an engine, or to hold down or choke.
The TPS sensor is a potentiometer type of electrical component. Rather than just being opened or closed like a switch, the TPS controls the circuit by varying its resistance in response to throttle position. In most cases this sensor will send a very low voltage back to the vehicle's main computer when the throttle plates are fully closed. This reference voltage rises as the throttle opens to increase speed. Keep in mind that some manufacturers use inverse voltage readings for feedback.