math help please?
2017-12-27 1:05 am
Two tankers, one 250 m in length and the other 110 m in length, travel parallel to each other at different but constant speeds. When travelling in opposite directions it takes them 15 seconds to pass each other, and when travelling in the same direction they take 60 seconds to pass each other. Find the difference in their speeds, metres/seconds.
回答 (2)
2017-12-27 1:24 am
Let a m/s and b m/s be the speeds of the tankers respectively, where a > b.
When travelling in the same direction they take 60 seconds to pass each other :
Difference in distance traveled in 60 s = The total length of the two tankers
60a - 60b = 250 + 110
60a - 60b = 360
a - b = 6
Difference in their speeds
= (a - b) m/s
= 6 m/s
When travelling in the same direction they take 60 seconds to pass each other :
Difference in distance traveled in 60 s = The total length of the two tankers
60a - 60b = 250 + 110
60a - 60b = 360
a - b = 6
Difference in their speeds
= (a - b) m/s
= 6 m/s
2017-12-27 1:25 am
It takes 15 seconds to cover 360 meters when their speeds are combined
(a + b) * 15 = 360
a + b = 360/15
a + b = 24
It takes 60 seconds to cross 360 meters when one speed is taken from the other
(a - b) * 60 = 360
a - b = 6
a + b = 24
a - b = 6
a + b + a - b = 24 + 6
2a = 30
a = 15
a - b = 6
15 - b = 6
b = 15 - 6
b = 9
15 - 9 = 6
(a + b) * 15 = 360
a + b = 360/15
a + b = 24
It takes 60 seconds to cross 360 meters when one speed is taken from the other
(a - b) * 60 = 360
a - b = 6
a + b = 24
a - b = 6
a + b + a - b = 24 + 6
2a = 30
a = 15
a - b = 6
15 - b = 6
b = 15 - 6
b = 9
15 - 9 = 6
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