Death Wheel
Kind advise to have patience in reading the problem. Thanks.
Assume you are the last hope of your nation to kill the dangerous enemy.
You can not go in straight fighting with him.
So now you have designed your own automatic death machine. There are 2 wheels in the machine. Big wheel is attached to small wheel and in return small wheel is attached to a electronic motor on the roof.
You have calculated that for every one rotation of small wheel, big wheel completes only 48% of its total rotation. Big wheel makes distance of 50 meters when it completes one rotation.
There is a pressure button on the road. Machine will start automatically when enemy passes it.
Enemy is 1260 meters far from pressure button and pressure button is 1750 meters far from impact area. And death wheel is exactly 3000 meters far from impact area. (See my poorly drawn blue print)
Travelling speed of enemy is 70 meters per minute.
How much time will you set in the machine for completion of one rotation of small wheel (in seconds) so that enemy will get killed automatically..??
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Distance from pressure button to impact area is 1750 meters. And speed of enemy's traveling is 70 meters per minute. So to cover 1750 meters he will take 1750/70 = 25 minutes in which time our death wheel must complete its journey of 3000 meters. So now calculate rotation to be completed by big wheel in 3000 meters. It is 3000/50 = 60 rotations to be completed. In return small wheel must have to complete 60/0.48 = 125 rotations in 25 minutes. So now simply calculate time to be taken to complete one rotation. = 25 minutes/125 rotations = 0.2 minute or 12 seconds.