Speed in m/sec = speed in km/hr x (5 / 18 )
Speed in m/sec = ( 36 x 5/18 ) m/sec
= 10 m/sec
Speed in m/sec = speed in km/hr x (5 / 18 )
Speed in m/sec = ( 30.6 x 18 /5 ) m/sec
= 8.5 m/sec
Speed in km/hr = speed in m/sec x (18 / 5 )
Speed in km/hr = ( 55 x 18 /5 ) km/hr
= 198 km/hr.
Speed in km/hr = speed in m/sec x (18 / 5 )
Speed in km/hr = (22.5 x 18 /5 ) km/hr
= 81 km/hr.
Average Speed = Total distance / time
= 2d / [( d / 16) + ( d / 9)]
= ( 2 x 16 x 9 ) / ( 16 + 9 ).
= 11.52 km/hr.
Shortcut :
Average speed = 2uv / (u + v)
= ( 2 x 16 x 9 ) / ( 16 + 9 )
= 11.52
Speed = 600 / (5 x 60) m/sec.
= 600 / (5 x 60) x 18/5 km/hr.
= 7.2 km/hr.
Length of two sides of square
= 8 x 1/2 km.
= 4 km.
? Area of the field = 2 x 2 sq. km
= 4 sq. km.
Average speed = 2uv / (u + v)
= ( 2 x 35 x 45) / (35 + 45) km/hr.
= 39 3/8 km/hr
Let distance covered by boy is Y.
Then, 25 : 10 : : 1000 : Y
? Y = (10 x 1000)/25 = 400 m
Ratio of speed = 2 : 3
Ratio of times taken for same distance = 1/2 : 1/3
From question 1/2 : 1/3 = t : 36
? (1/3) x t = (1/2) x 36
? x = 54 min .
Average speed = 2uv / ( u + v ) km/hr
=(2 x 64 x 80) / (64 + 80) km/hr
= (2 x 64 x 80) / 144 km/hr.
= 71.11 km/hr
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