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.
Boys of the same age need an average of 2,000 calories each day, so protein should account for 200 to 600 of their calories. Boys and girls 9 to 13 need the same .95 grams of protein for each kilogram of body weight, making the recommended dietary allowance for kids in this range 34 grams per day.he Institute of Medicine recommends kids between the ages of one and three eat enough protein to account for 5 to 20 percent of their total calorie intake each day. For a moderately active child who averages 1,200 calories per day, between 60 and 240 of those calories should come from protein sources.