Lesson on Calculating Speed as a Compound Measure of Distance and Time

Introduction

• Formula for Speed: Speed is calculated as distance divided by time.
• Units are important: e.g., kilometers per hour (km/h) or miles per hour (mph).

Example Problems

Question 1

• Scenario: Car travels 450 kilometers in 5 hours.
• Calculation:
  • Speed = Distance / Time = 450 km / 5 hours = 90 km/h.

Question 2

• Scenario: Plane travels between New York and California.
• Details:
  • Distance: 2,900 miles.
  • Time: 8am to 12:30pm = 4.5 hours.
• Calculation:
  • Average Speed = 2,900 miles / 4.5 hours ≈ 644.4 mph.

Question 3

• Scenario: Van travels 160 kilometers at 40 km/h.
• Objective: Find the travel time.
• Calculation:
  • Speed = Distance / Time.
  • Rearrange for Time: Time = Distance / Speed = 160 km / 40 km/h = 4 hours.

Question 4

• Scenario: Two-part journey involving walking and cycling.
• Details:
  • Part 1: Walks 5 km at 8 km/h.
  • Part 2: Cycles 6 km at 12 km/h.
• Calculations:
  • Part 1 Time: 5 km / 8 km/h = 0.625 hours.
  • Part 2 Time: 6 km / 12 km/h = 0.5 hours.
  • Total Time: 0.625 + 0.5 = 1.125 hours.
  • Total Distance: 5 km + 6 km = 11 km.
  • Average Speed for Journey: Total Distance / Total Time = 11 km / 1.125 hours = 8.8 km/h.

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Conclusion

• Practice using the speed formula to solve various problems involving distance and time.
• Understanding of rearranging formulas to find unknown variables is crucial.

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Note: Always include the appropriate units when calculating speed, distance, or time.