📚 Time‑Speed‑Distance (TSD) – Quick Study Notes
(For Andaman & Nicobar Islands TET – Quantitative Aptitude)
1. What is it?
- Time: How long something takes.
- Speed (or Velocity) : How fast something moves.
- Distance: How far it goes.
Think of a road trip:
- Distance = miles between two cities.
- Speed = how fast you drive (mph).
- Time = how many hours the trip takes.
2. The Basic Relationship
Distance = Speed × Time
So, if you know any two of the three, you can find the third.
| You know | Find | Formula |
|---|---|---|
| Speed & Time | Distance | D = S × T |
| Distance & Time | Speed | S = D ÷ T |
| Distance & Speed | Time | T = D ÷ S |
Remember: All units must match (e.g., km & h, or m & s).
3. Simple Everyday Examples
| Scenario | What you know | What you need | Calculation |
|---|---|---|---|
| Drive 150 km in 3 hours | Distance & Time | Speed | S = 150 ÷ 3 = 50 km/h |
| Walk 5 km in 1 hour | Speed & Time | Distance | D = 5 × 1 = 5 km |
| Bike 80 km at 20 km/h | Speed & Distance | Time | T = 80 ÷ 20 = 4 h |
4. Quick Tips for TET
| Tip | Why it helps |
|---|---|
| Convert units first | Avoids mistakes (e.g., 60 min = 1 h). |
| Check the “given” | The problem always tells you what you have. |
| Use “÷” for speed or time | Speed = Distance ÷ Time; Time = Distance ÷ Speed. |
| Double‑check the result | Make sure units match (km, km/h, h). |
5. Common Pitfalls
| Mistake | Fix |
|---|---|
| Mixing km and miles | Convert everything to one unit. |
| Forgetting to divide when finding speed | Speed = Distance ÷ Time, not Distance × Time. |
| Adding instead of multiplying | Remember the formula is multiplication for distance. |
6. Mini‑Practice Problems
| # | Problem | Solve | Answer |
|---|---|---|---|
| 1 | A car travels 120 km in 2 h. What is its speed? | S = 120 ÷ 2 |
60 km/h |
| 2 | A train covers 240 km in 4 h. Find the time needed to cover 360 km at the same speed. | First, S = 240 ÷ 4 = 60 km/h. Then, T = 360 ÷ 60. |
6 h |
| 3 | A cyclist rides at 15 km/h for 3 h. How far does he go? | D = 15 × 3 |
45 km |
7. Quick Check Quiz
- A bus covers 90 km in 3 hours. What is its average speed?
- If a plane travels 1800 km at 600 km/h, how long does the flight last?
- A student walks 4 km in 30 minutes. What is his speed in km/h?
(Try to solve before looking at the answers below.)
Answers
- 30 km/h
- 3 hours
- 8 km/h
8. Final Thought
Time, speed, and distance are like friends that always play together:
- Distance = Speed × Time
- Speed = Distance ÷ Time
- Time = Distance ÷ Speed
Keep the formula in mind, practice a few problems, and you’ll ace this section of the TET! 🚀