Question 1

Why must equations in engineering calculations be dimensionally homogeneous?

Accepted Answer

Dimensional homogeneity ensures that all terms in an equation are expressed in the same units, maintaining consistency regardless of the equation being assessed. This requirement is fundamental to numerical calculations in engineering applications, as it guarantees that results are physically meaningful and can be reliably compared across different problem contexts.

Question 2

How should large and small numbers be expressed in engineering notation?

Accepted Answer

Large numbers are expressed in multiples of 10³, while small numbers are expressed in multiples of 10⁻³. For example, 34,600 can be written as 34.6(10³) with three significant figures. Beginning zeros in decimals are insignificant; 0.00456 has only three significant figures and is expressed as 4.56(10⁻³).

Question 3

What is the rounding rule when a number ends with the digit five?

Accepted Answer

When a number ends with digit five, it is rounded up only if the preceding digit is odd. If the preceding digit is even, the number remains unchanged up to the required significant figures. This rule ensures consistent and unbiased rounding in numerical calculations.

Question 4

When should rounding be applied during multi-step engineering calculations?

Accepted Answer

Rounding should not be applied until the final step of a calculation. While performing several intermediate steps, maintain full calculator precision to preserve accuracy. Only the final answer or result should be rounded based on the required accuracy, typically to three significant figures in most engineering applications.

Question 5

How do significant figures affect the accuracy of numerical results?

Accepted Answer

The number of significant figures contained in a numerical value is a critical factor determining accuracy. Results are rounded to the required significant figures and expressed using engineering notation to avoid confusion from trailing zeros. Knowing how many significant figures to use ensures the final result maintains appropriate accuracy for the engineering application.

Question 6

What methods are commonly used to solve engineering problems numerically?

Accepted Answer

Engineering problems are solved using three primary methods: manual algebraic symbol manipulation, graphical methods, and computer-based approaches. Handheld calculators or computers are preferred for numerically accurate answers. Computers become essential when many equations must be solved simultaneously, providing efficiency and precision in complex problem solving.

Question 7

Why are prefixes used to express numerical values in engineering?

Accepted Answer

Prefixes are used to express large or small numbers in a standardized, readable format. They eliminate confusion from trailing zeros and make values easier to communicate and compare. Using prefixes with engineering notation ensures that numerical results are presented clearly and consistently across engineering applications and problem solving in statics.

Calculs numériques

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