Elapsed time

Learning Objectives Calculate elapsed time between two given times, including intervals that cross midnight and span multiple days. Determine a start or end time given the other time and the duration of an event. Apply the concept of elapsed time to solve rate problems involving speed, distance, and time. Convert between different units of time (seconds, minutes, hours) and express time in various formats (12-hour, 24-hour, decimal hours). Set up and solve proportions involving elapsed time and other quantities, such as work completed or volume filled. Analyze multi-step word problems that require calculating and summing multiple elapsed time intervals. Use algebraic expressions to represent unknown time variables in elapsed time problems. Ever wonder how your GPS instantl...

TermDefinitionExample Elapsed TimeThe duration of an event, measured as the amount of time that passes from a specific start time to a specific end time.If a lab experiment begins at 10:40 AM and concludes at 1:15 PM, the elapsed time is 2 hours and 35 minutes. 24-Hour Time (Military Time)A timekeeping convention where the day runs from 00:00 (midnight) to 23:59. It eliminates the need for AM/PM, which simplifies elapsed time calculations.8:30 AM is 08:30, and 4:45 PM is 16:45. The elapsed time between them is 16:45 - 08:30 = 8 hours and 15 minutes. Decimal TimeThe representation of a time duration as a decimal number, typically in hours. This format is essential for use in rate formulas.3 hours and 45 minutes is converted to decimal hours by dividing the minutes by 60: 45 / 60 = 0.75. Th...

Elapsed Time Calculation Elapsed Time = End Time - Start Time To find the duration of an event. For best results, convert both times to 24-hour format first to avoid AM/PM errors and simplify calculations, especially when crossing midnight. The Fundamental Rate Formula Speed = Distance / Time (s = d / t) This formula and its algebraic rearrangements (d = s * t, t = d / s) are the foundation for solving problems involving motion. The 'Time' variable is the elapsed time, which must be in a single unit (e.g., decimal hours) that matches the rate's unit. Proportional Reasoning with Time (Quantity_1 / Time_1) = (Quantity_2 / Time_2) Use this structure when a rate is constant over different time intervals. It allows you to solve for an unknown quantity or t...