Answers:
500meters
Explanation:
Speed = | 78 x | 5 | m/sec | = | 65 | m/sec. | ||||
18 | 3 |
Time = 1 minute = 60 seconds.
Let the length of the tunnel be x metres.
Then, | 800 + x | = | 65 | ||
60 | 3 |
3(800 + x) = 3900
x = 500
Speed = | 78 x | 5 | m/sec | = | 65 | m/sec. | ||||
18 | 3 |
Then, | 800 + x | = | 65 | ||
60 | 3 |