Distance–Rate–Time Problems
Build one distance equation for each traveler, then connect the distances using the story.
Distance–Rate–Time Problems
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Build one distance equation, then connect the travelers
The core relationship is d=rt, but UPCAT-style questions usually hide which distance, rate, or time belongs in the equation.
Convert units before calculating. For an entire trip, average speed is total distance ÷ total elapsed time, including stops. When travelers move toward each other, add their speeds. For catch-up in the same direction, subtract their speeds.
Draw the distance or gap
Mark starting points, direction, speed, and any delayed departure.
Use relative speed carefully
Towardopposite directions usually add; catching up in one direction uses a difference.
Decide what happens to the gap
Problem: Two vehicles are 180 km apart and move toward each other at 50 kmh and 40 kmh.
Recognize: Every hour, the first closes 50 km of the gap and the second closes 40 km. Together they close 90 km per hour.
time = 180(50+40) = 2 hoursFor a same-direction catch-up, use the faster speed minus the slower speed because only that difference reduces the lead.
Why it works
Relative speed measures how quickly the distance between travelers changes. Adding or subtracting rates is justified by whether both motions reduce the gap or only one traveler gains on the other.
Five forms you should recognize
A van travels at 60 kmh for 2.5 hours.
d=rt=60(2.5)=150 kmA trip covers 150 km in 2.5 hours of driving and includes a 30-minute stop. Total elapsed time is 3 hours:
average speed=1503=50 kmhTwo vehicles 240 km apart approach at 50 kmh and 70 kmh.
closing speed=50+70=120 kmhtime=240120=2 hoursA slower vehicle has a 45-km lead at 60 kmh; a faster one follows at 75 kmh.
gain speed=75−60=15 kmhtime=4515=3 hoursA car travels 120 km at 60 kmh and returns 120 km at 40 kmh.
total distance=240 kmtotal time=12060+12040=2+3=5 haverage speed=2405=48 kmhDo not simply average 60 and 40 because the car spends different amounts of time at the two speeds.
Check before you commit
- Mixing minutes with hours
- Averaging speeds instead of using total distance over total time
- Ignoring stopped time
- Adding speeds in a same-direction catch-up
- Subtracting speeds when travelers approach each other
- Finding meeting time but not the requested meeting location
Do you need the lesson-or just practice?
One original question in each form recommends your next step. It does not yet verify mastery.
Work at the level you need.
Foundations
Build the core procedure with immediate explanations.
Core Practice
Use mixed forms with less scaffolding.
UPCAT-Style Transfer
Apply the competency in unfamiliar representations.
Ready to verify this competency?
A score of 5/5 verifies mastery. An unsuccessful attempt loads a different five-form bank.
Distance–Rate–Time Problems FAQ
Why are there two mastery sets?
An unsuccessful attempt loads a different five-question set so memorizing one set does not verify mastery.
Does 5/5 mean permanent mastery?
It verifies the competency today. Revisit it later through mixed practice and simulations.
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