🎙 Teacher-Style Introduction

Time, Speed & Distance वह chapter है जहाँ concept सिर्फ एक है — Distance = Speed × Time. Delhi Police exam में 2–3 सवाल direct इसी formula पर आधारित आते हैं।

Train, car, walking speed — सारे questions आसान और calculation-friendly होते हैं।

📘 Important Formulas / महत्वपूर्ण सूत्र

• Distance = Speed × Time
• Speed = Distance / Time
• Time = Distance / Speed
• 1 km/hr = 5/18 m/s
• 1 m/s = 18/5 km/hr
• Relative Speed (Same direction) = A − B
• Relative Speed (Opp direction) = A + B

• दूरी = गति × समय
• गति = दूरी / समय
• समय = दूरी / गति
• 1 किमी/घंटा = 5/18 मी/से
• विपरीत दिशा = गति जोड़ें
• एक ही दिशा = गति घटाएँ

⚡ Tricks & Shortcuts

• Unit conversion हमेशा check करें (km/hr ↔ m/s).
• Relative speed वाले questions fastest होते हैं (2-step).
• DP exam में tough train questions नहीं आते — सिर्फ basic TSD.
• “Speed doubled → time half” type relations याद रखें।

✔ Solved Examples / हल प्रश्न

Example 1: Speed = 40 km/hr, Time = 2 hours. Find distance.
→ D = 40×2 = 80 km

Example 2: D = 150 km, S = 50 km/hr → Time?
→ T = 150/50 = 3 hr

Example 3: Convert 54 km/hr into m/s.
→ 54 × 5/18 = 15 m/s

Example 4: Convert 10 m/s into km/hr.
→ 10 × 18/5 = 36 km/hr

Example 5: Two cars at 40 & 30 km/hr opposite direction.
→ Relative speed = 70 km/hr

Example 6: Two persons walk at 5 km/hr & 3 km/hr same direction.
→ Relative = 2 km/hr

Example 7: A car covers 120 km in 3 hours. Find speed.
→ S = 120/3 = 40 km/hr

Example 8: A man increases speed from 10 to 20 km/hr. Time becomes?
→ Time becomes half.

✔ MCQs (Delhi Police Pattern)

1. Speed = 60 km/hr, Time = 2 hr. Distance? Ans: 120 km
2. Distance = 90 km, Speed = 30 km/hr. Time? Ans: 3 hr
3. Convert 36 km/hr to m/s. Ans: 10 m/s
4. Convert 20 m/s to km/hr. Ans: 72 km/hr
5. Opp direction: 45 & 55 km/hr. Relative speed? Ans: 100 km/hr
6. Same direction: 50 & 30 km/hr. Relative speed? Ans: 20 km/hr
7. Time = 4 hr, Distance = 200 km. Speed? Ans: 50 km/hr
8. A man walks 4 km/hr, runs 8 km/hr. Ratio of times? Ans: 2 : 1
9. A covers 150 km in 5 hours → speed? Ans: 30 km/hr
10. If speed × time = 180, distance = ? Ans: 180

💡 Motivation: Speed important है, पर direction उससे भी ज्यादा — exam में भी और जिंदगी में भी! 🚓🔥