A police spotted a burglar from $$100\text{m}$$ apart. The burglar immdiately runs away at a speed of $$4\text{m/s}$$ and the police starts chasing him at $$8\text{m/s}$$ at the same time. At this rate, how long will it take the police to catch the burglar? 
Overseas Competition->Knowledge Point->Distance Word Problems->Distance Word Problems on Straight Road
The distance between them is $$100$$ m, and the difference between their speeds is $$12-8=4000$$ m/h. It takes $$100\div4000\times60=1.5$$minutes to catch the burglar, which is $$90$$ seconds 