Speed, Distance, Time, Knowledge Organiser

Key Terms

• Speed: The distance travelled per unit of time
• Average speed: Total distance divided by total time for a journey
• Distance: The length of the path travelled
• Time: The duration of travel
• Units: Speed in km/h or m/s; distance in km or m; time in hours or seconds

Must-Know Facts

• Speed = Distance ÷ Time
• Distance = Speed × Time
• Time = Distance ÷ Speed
• Units MUST match: km/h needs distance in km and time in hours
• Convert time to decimal hours: 30 min = 0.5 h; 45 min = 0.75 h; 90 min = 1.5 h
• Average speed = total distance ÷ total time (NOT average of two speeds)

Key Formulas

• S = D ÷ T
• D = S × T
• T = D ÷ S
• Cover the letter you want in the DST triangle to find the formula

Common Mistakes

• Time as decimals: 1 hr 30 min = 1.5 hours, NOT 1.3 hours: convert minutes by dividing by 60
• Unit mismatch: Speed in km/h but distance in metres: convert to matching units first
• Average speed: Total distance ÷ total time: cannot just average two speeds
• Rearranging incorrectly: D = S × T, so T = D ÷ S (not D × S)

Worked Examples

A car travels 150 km in 2.5 hours. Calculate the average speed. Step 1 Write the formula Speed = Distance ÷ Time Step 2 Substitute values Speed = 150 ÷ 2.5 Step 3 Calculate Speed = 60 km/h Answer: 60 km/h