Speed, Distance & Time - Shortcuts & Tricks for Placement Tests, Job Interviews & Exams, by CareerRide on YouTube. 41 min 42 s.
- Video length
- 41 min 42 s
- Time to do it
- 20 minutes
- Difficulty
- Easy
- Steps
- 8
What you need
Steps
Write down the three formulas: speed equals distance divided by time, distance equals speed times time, and time equals distance divided by speed.
Convert every measurement to matching units before you calculate. To change km/h to m/s, multiply by 5/18. To change m/s to km/h, multiply by 18/5.
For a journey split into equal distances at two different speeds, use average speed equals 2xy divided by x plus y. Do not simply average the two speeds.
Use ratio logic when one value stays fixed. At constant distance, speed and time are inversely proportional. At constant time, distance and speed are directly proportional.
For train questions, use the train length when it passes a pole or person. Add the platform or bridge length when the whole train must clear it.
For relative motion, add speeds when objects move toward each other and subtract them when they move in the same direction. Draw a simple line diagram first.
For boats and streams, use downstream speed equals boat speed plus stream speed, and upstream speed equals boat speed minus stream speed. Then solve the two equations.
Check each answer by putting it back into the formula, confirming the units, and comparing it with the answer options. Estimate first to catch impossible results.
Tips and common mistakes
Keep minutes in hours for km/h questions, or convert everything to metres and seconds.
Do not use the simple average for equal-distance speed questions; the harmonic mean gives the correct result.
Write the unit beside every number so you notice a mismatch before you finish.
Practise under a timer and review wrong answers by error type, not just by topic.
Questions
What is the basic formula for speed?
Speed equals distance divided by time. Rearrange it to get distance equals speed times time, or time equals distance divided by speed.
How do I convert km/h to m/s quickly?
Multiply the speed in km/h by 5/18. For example, 36 km/h becomes 10 m/s.
Why is average speed not just the average of two speeds?
The simple average works only when the times are equal. For equal distances at different speeds, use 2xy divided by x plus y.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
