In the figure, the lever arm, l, is distance r from the hinge to the point at which you exert your force. The torque is the product of the magnitude of the perpendicular force multiplied by the lever arm.
Children normally need a certain number of calories each day (energy allowance) that their bodies use as energy for normal daily activities (walking, breathing, etc.). This ranges for boys from 2000 calories for a 7-10 year old, 2500 calories for an 11-14 year old, and 3000 calories for a 15-18 year old. For girls the ranges are from 2000 calories for a 7-10 year old, to 2200 calories for an 11-18 year old. These are only estimates and some children need more (fast metabolism) or less (slow metabolism) of an energy allowance for daily activities.
According to the Dietary Guidelines for Americans 2010, sedentary teen girls ages 13 to 18 need about 1,600 to 1,800 calories a day, while sedentary teen boys within the same age range require about 2,000 to 2,400 calories daily to maintain healthy body weights. teenagerâs daily calorie needs are highly dependent on his size and activity level. However, general guidelines exist to give you and your teen a good idea of how many calories he should consume each day.