1. Speed = [Distance/Time],
Time=[Distance/Speed],
Distance = (Speed*Time)
2. x km/hr = [x*5/18] m/sec.
3. If the ratio of the speeds of A and B is a:b, then the ratio of the times taken by them to cover the same distance is 1/a : 1/b or b:a.
4. x m/sec = [x*18/5] km/hr.
5. Suppose a man covers a certain distance at x km/hr and an equal distance at y km/hr. then, the average speed during the whole journey is [2xy/x+y] km/hr.
BOATS AND STREAMS -> IMPORTANT FACTS AND FORMULAE
I. In water, the direction along the stream is called downstream. And, the direction against the stream is called upstream.
II. If the speed of a boat in still water is u km/ht and the speed of the stream is v km/hr, then : Speed downstream = (u + v) km/hr Speed upstream (u - v) km/hr.
III. If the speed downstream is a km/hr and the speed upstream is b km/hr, then : Speed in strill water = 1/2 (a + b) km/hr Rate of stream = 1/2 (a - b) km/hr
2. x km/hr = [x*5/18] m/sec.
3. If the ratio of the speeds of A and B is a:b, then the ratio of the times taken by them to cover the same distance is 1/a : 1/b or b:a.
4. x m/sec = [x*18/5] km/hr.
5. Suppose a man covers a certain distance at x km/hr and an equal distance at y km/hr. then, the average speed during the whole journey is [2xy/x+y] km/hr.
BOATS AND STREAMS -> IMPORTANT FACTS AND FORMULAE
I. In water, the direction along the stream is called downstream. And, the direction against the stream is called upstream.
II. If the speed of a boat in still water is u km/ht and the speed of the stream is v km/hr, then : Speed downstream = (u + v) km/hr Speed upstream (u - v) km/hr.
III. If the speed downstream is a km/hr and the speed upstream is b km/hr, then : Speed in strill water = 1/2 (a + b) km/hr Rate of stream = 1/2 (a - b) km/hr
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