Numerical work in engineering practice is most often performed by using handheld calculators and computers. It is important, however, that the answers to any problem be reported with justifiable accuracy using appropriate significant figures. In this section we will discuss these topics together with some other important aspects involved in all engineering calculations. Dimensional Homogeneity. The terms of any equation used to describe a physical process must be dimensionally homogeneous; that is, each term must be expressed in the same units. Provided this is the case, all the terms of an equation can then be combined if numerical values are substituted for the variables. Consider, for example, the equation s = vt +ar, where, in SI units, s is the position in meters, m, 1 is time in seconds, s, v is velocity in m/s and a is acceleration in m/s2. Regardless of how this equation is evaluated, it maintains its dimensional homogeneity. In the form stated, cach of the three terms is expressed in meters [m, (m/x)x. (m/ or solving for a, a = each expressed in units of m/s [m/s², m/s². (m/s)/s]. Keep in mind that problems in mechanics always involve the solution of dimensionally homogeneous cquations, and so this fact can then be used as a partial check for algebraic manipulations of an equation. 2s/r- 2v/t, the terms are

Numerical work in engineering practice is most often performed by using handheld calculators and computers. It is important, however, that the answers to any problem be reported with justifiable accuracy using appropriate significant figures. In this section we will discuss these topics together with some other important aspects involved in all engineering calculations. Dimensional Homogeneity. The terms of any equation used to describe a physical process must be dimensionally homogeneous; that is, each term must be expressed in the same units. Provided this is the case, all the terms of an equation can then be combined if numerical values are substituted for the variables. Consider, for example, the equation s = vt +ar, where, in SI units, s is the position in meters, m, 1 is time in seconds, s, v is velocity in m/s and a is acceleration in m/s2. Regardless of how this equation is evaluated, it maintains its dimensional homogeneity. In the form stated, cach of the three terms is expressed in meters [m, (m/x)x. (m/ or solving for a, a = each expressed in units of m/s [m/s², m/s². (m/s)/s]. Keep in mind that problems in mechanics always involve the solution of dimensionally homogeneous cquations, and so this fact can then be used as a partial check for algebraic manipulations of an equation. 2s/r- 2v/t, the terms are