Time Distance Speed

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Flashcards(15)

Time, Speed & Distance (TSD) - CAT Preparation

What is the fundamental relationship between time, speed, and distance expressed in its most basic formula?

Distance = Speed × Time. This is the core equation from which all other TSD relationships are derived.

If speed is doubled while time remains constant, what happens to the distance covered?

Distance doubles. This demonstrates the direct proportionality between speed and distance when time is constant.

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How is relative speed calculated for two objects moving in opposite directions?

Relative speed = Speed₁ + Speed₂. Their speeds add up because they are closing the gap between them.

How is relative speed calculated for two objects moving in the same direction?

Relative speed = |Speed₁ - Speed₂|. It is the absolute difference, representing the rate at which the gap between them changes.

In boats and streams problems, what is the formula for the speed of the boat in still water given its upstream and downstream speeds?

Speed in still water = (Downstream Speed + Upstream Speed) / 2. This averages out the effect of the stream's current.

How do you calculate the speed of the stream in a boats and streams problem?

Speed of stream = (Downstream Speed - Upstream Speed) / 2. This isolates the current's contribution to the boat's speed.

On a circular track, if two runners start from the same point and run in the same direction, when do they meet for the first time?

They meet when the faster runner gains one full lap on the slower runner. The time is Track Length / Relative Speed (difference).

On a circular track, if two runners start from the same point and run in opposite directions, when do they meet for the first time?

They meet when the sum of the distances covered equals the track length. The time is Track Length / Relative Speed (sum).

What is the correct method to calculate average speed for a journey with multiple parts?

Average Speed = Total Distance / Total Time. You must calculate the time for each segment individually before summing.

Why is it incorrect to simply average the speeds of different journey segments to find the overall average speed?

Because average speed is a weighted harmonic mean based on time, not a simple arithmetic mean. It depends on the time spent at each speed.

When a train crosses a pole (a stationary object with negligible length), what distance does it cover?

The train covers a distance equal to its own length. Time taken = (Length of Train) / (Speed of Train).

When a train crosses a platform, what total distance must it cover?

It must cover the sum of its own length and the length of the platform. Time = (Train Length + Platform Length) / Speed.

According to CAT strategy, what type of TSD questions are considered 'low-hanging fruit' and should be attempted first?

Questions involving direct formula application (Average Speed, Relative Speed), simple boats & streams, or train lengths.

What is a key time-saving mental math conversion to remember for TSD problems?

To convert km/h to m/s, multiply by 5/18. To convert m/s to km/h, multiply by 18/5.

What is the recommended time allocation per TSD question in the CAT exam?

Aim for 1.5 to 2.5 minutes per question. Use strategies like backsolving from options or approximation to save time.