A car moves a distance of 200m it cover the first half of the distance at a speed of 60km/h.and the second half of distance at speed v . If the average speed is 40km/h , then the value of v is
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speed at first half = ( 60 × 1000)/(60 × 60) = 100/6
average speed = 200/ t
t = 100/(100/6) + 100/(v)
av speed = 200/{100/(100/6)+ 100/(v)}
= 200/{(100v + 10000/6)/(100v/6)}
=20000v/6 /{( 600v + 10000)/6}
20000V/(600V+10000)
20000V= (40 ×1000)/(60×60) ×( 600V +10000)
20000V = 400/36 × ( 600V + 10000)
20000V =( 100/9 * 600V) + 100/9 * 10000
20000V = 60000V/9 + 1000000/9
(180000V - 60000V)/9 = 1000000/9
120000V / 9 = 1000000/9
V = 1000000/ 120000
V = 100/ 12 = 8.3ms
= 29.880 km / hr
average speed = 200/ t
t = 100/(100/6) + 100/(v)
av speed = 200/{100/(100/6)+ 100/(v)}
= 200/{(100v + 10000/6)/(100v/6)}
=20000v/6 /{( 600v + 10000)/6}
20000V/(600V+10000)
20000V= (40 ×1000)/(60×60) ×( 600V +10000)
20000V = 400/36 × ( 600V + 10000)
20000V =( 100/9 * 600V) + 100/9 * 10000
20000V = 60000V/9 + 1000000/9
(180000V - 60000V)/9 = 1000000/9
120000V / 9 = 1000000/9
V = 1000000/ 120000
V = 100/ 12 = 8.3ms
= 29.880 km / hr
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