Tips and Tricks for Speed, Distance and Time (original) (raw)

Last Updated : 23 Jul, 2025

Speed, Time, and Distance questions are foundational in quantitative aptitude exams, often determining time management and problem-solving speed.

This topic is crucial because it tests mathematical skills and evaluates a candidate’s logical thinking and ability to apply formulas effectively under pressure.

Key Formulas for Speed, Distance, and Time

**Basic Formulas for Speed, Distance, and Time:

• **Speed = Distance / Time
• **Distance = Speed × Time
• **Time = Distance / Speed

These formulas can be remembered using a simple acronym **DST where **D stands for **Distance, **S for **Speed, and **T for **Time, and can be visualized as below:

Speed, Distance and Time Formula

Unit Conversion Tips

Here is a table to convert various units.

Shortcut Tricks for Speed Distance and Time Questions

Average Speed for Varying Distances

**Formula:

**Average Speed = Total Distance/Total Time

**When to Use: This formula is helpful when a journey consists of different distances covered at different speeds.

Average Speed for Equal Distances at Different Speeds

**Formula:

**Average Speed = (2 × Speed 1 × Speed 2)/(Speed 1 + Speed 2)

**When to Use: Use this formula when covering equal distances at two different speeds, such as going to a location at one speed and returning at another.

Relative Speed

Relative speed helps understand the effective speed between two moving objects, useful for solving problems involving trains, cars, or boats.

• **Same Direction:
  • Relative Speed = Difference of Speeds
    * **Example**:** Two trains moving at 80 km/h and 60 km/h in the same direction:
    * Relative Speed = 80 - 60 = 20 km/h
• **Opposite Directions:
  • Relative Speed = Sum of Speeds
    * **Example**:** Two trains moving at 80 km/h and 60 km/h toward each other:
    * Relative Speed = 80 + 60 = 140 km/h

Time to Meet or Overtake

• **Meeting Time:
  • **Time = Distance ÷ Relative Speed
  • **Example****:** Two cars 300 km apart moving toward each other at 50 km/h and 70 km/h:
    * Relative Speed = 50 + 70 = 120 km/h
    * Time = 300 ÷ 120 = 2.5 hours
• **Overtaking Time:
  • **Time = Distance ÷ Relative Speed
  • **Example****:** A faster car overtaking a slower car 100 meters ahead, with speeds of 20 m/s and 15 m/s respectively:
    * Relative Speed = 20 - 15 = 5 m/s
    * Time = 100 ÷ 5 = 20 seconds

Train Problems

**Passing a Stationary Object: When a train passes a stationary object, the distance covered is equal to the length of the train.

**Formula: Time = Length of Train ÷ Speed

**Example: A train 275 meters long is moving at a speed of 66 km/h. How long will it take for the train to pass a stationary signal post?

Length of Train = 275 meters

Speed = 68 km/h

• Convert speed to meters per second:
  • Speed = 68 × (5/18) ≈ 18.89 m/s
• Time = Length of Train ÷ Speed
  • 275 ÷ 18.89 ≈ 14. 56 seconds

The train will take approximately **14.56 seconds to pass the stationary signal post completely.

**Train Passing a Platform: When a train passes a platform, the distance covered is the sum of the lengths of the train and the platform.

**Formula: Time = (Length of Train + Length of Platform) ÷ Speed

**Example: A train 225 meters long is traveling at a speed of 60 km/h. How long will it take for the train to completely pass a platform that is 180 meters long?

Length of Train = 225 meters

Length of Platform = 180 meters

Speed = 60km/h

• **Convert Speed to Meters per Second:
  • Speed = 60 × (5/18) = 16.67 m
• **Calculate Total Distance to Pass the Platform:
  • Total Distance = Length of Train + Length of Platform
  • Total Distance = 225 meters + 180 meters = 405 meters
• **Calculate Time to Pass the Platform:
  • Time = Total Distance ÷ Speed
  • Time = 405 meters ÷ 16.67 m/s ≈ 24.3 seconds

The train will take approximately **24.3 seconds to pass the stationary signal post completely.

**Related Reads:

• Speed, Time, and Distance.
• Practice Quiz on Speed Time and Distance.
• Problem on Time Speed and Distance