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CBSE Class 11-science Answered

What is relative velocity
Asked by dibyanshubehera2727 | 02 Jul, 2021, 07:28: AM
answered-by-expert Expert Answer
When an object is moving in a medium, if medium also under motion , then the motion of medium
observed from the moving object is called relative motion. 
 
Velocity of moving medium observed from the object is relative velocity.
This is because velocity observed by an observer who is at rest is differenct from the velocity observed by an observer in the moving object.
 
Let us consider the example of boat moving in a river.
Let u be the velocity of river and v be the velocity of boat. 
 
In the upstream direction, i.e., when boat moving in the direction opposite to the direction of motion of river ,
velocity of river observed by observer in the boat is ( u+v )
 
In the downstream direction. i.e., when boat moving in same direction as the direction of motion of river ,
velocity of river observed by observer in the boat is ( u - v )
 
Answered by Thiyagarajan K | 02 Jul, 2021, 09:04: AM

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CBSE 11-science - Physics
What is relative velocity
Asked by dibyanshubehera2727 | 02 Jul, 2021, 07:28: AM
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CBSE 11-science - Physics
According to relative velocity formula we know that when two bodies move towards each other the relative velocity is equal to the sum of two velocities. Then why in calculating upstream where the direction of velocity of stream is against the direction of velocity of boat in still water we subtract the former from the latter even when they are opposite to each other? 
Asked by ahanaganguly55 | 28 May, 2021, 03:59: PM
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CBSE 11-science - Physics
A jet airplane traveling at the speed of 500 km/hr ejects its products of combustion at the speed of 1500 km/hr relative to the jet plane. What is the speed of the later with respect to an obserever on the ground? 
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CBSE 11-science - Physics
Two ships A and B strat together from the same point. A sails 16 km/h towards east and B sails 20 km/h towards north. Find the relative velocity of B w.r.t A and distance between them after 5 hours.
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
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CBSE 11-science - Physics
Two trains are moving in the opposite directions on parallel tracks, one with a velocity twice that of other. If the total length of the two trains is 480 ft and they take 3 seconds to cross each other, find their individual velocities.
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
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CBSE 11-science - Physics
In a harbour, wind is blowing at the speed of 72 km/h and a flag on the mast of the boat anchored in the harbour along the N-E direction. If the boat starts moving at a speed of 51 km/h to the north, what is the direction of the flag on the mast of the boat.
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
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CBSE 11-science - Physics
Two trains A and B of length 400 m each are moving on two parallel tracks with a uniform speed of 72 km/hr in the same direction, with A ahead of B.The driver of B decides to overtake A and accelerates by 1 m/s2 . If after 50s, the guard of B just brushes past the driver of A, what was the original distance between them?
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
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CBSE 11-science - Physics
Two cars A and B are moving with same speed 30 km/hr in same direction with car B 5 km behind the car A. Another car C moving in opposite direction crosses the two cars at an interval of 4 minutes. Find the speed of car C.
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CBSE 11-science - Physics
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Asked by Topperlearning User | 23 Apr, 2014, 07:39: AM
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