Aiyyo, forget all the big signs and conventions first. Just add their speeds if they are coming towards each other, subtract if one is going away from the other? No, no. For relative velocity, you always *add* the speeds when they move towards each other. Think of two scooters on this road – the closing gap is faster, so speeds add.
I remember this from helping my nephew with his homework, sitting right here on this sack of rice. We used to take his toy trains. The key is to take one train as reference and see the other's speed relative to it. If they are opposite directions, it's v1 + v2. Same direction, it's |v1 - v2|.
You decide the sign based on your reference. But in our village station, if the Dharmabad passenger and the Godavari Express are approaching, we just know they are coming fast. So for exam, stick to one direction as positive, then put the other velocity with its sign. Simple.
#exams#study
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