In the United States, the average age for a girl to get her first period is 12. This does not mean that all girls start at the same age. A girl can start her period anytime between the ages of 8 and 15. Most of the time, the first period starts about 2 years after breasts first start to develop. If a girl has not had her first period by age 15, or if it has been more than 2 to 3 years since breast growth started, she should see a doctor.
Cancel Save! You can build a balance beam out long pieces of wood covered with thick cloth, or sand it smooth so you don't get a splinter. A piece of wood laid on the ground is not a balance beam. Balance beams are 10 cm wide, 500 cm long, and usually 124 cm off the ground. Post Your Project.
Split and merge into it. Answer by Matthew Parker. Confidence votes 2.6K. A triple beam balance is a type of scale commonly used in the laboratory to determine the mass (by weight comparison) of samples. To use the balance, you use sliding weights called riders on three beams, each with progressively small incremental amounts.