A driver on a level two-lane highway observes a truck completely blocking the highway. The driver was able to stop her vehicle only 30 ft from the truck. If the driver was driving at 55 mi/h, how far was she from the truck when she first observed it (assume perception-reaction time is 1.5 seconds)?

Athin walled concentric tube exchanger is used to cool engine oil from 160°c to 60°c with water that is available at 25°c acting as a coolant. the oil and water flow rates are each at 2 kg/s, and the diameter of the inner tube is 0.5 m and the corresponding value of the overall heat transfer coefficient is 250 w/m2. oc. how long must the heat exchanger be to accomplish the desired cooling? cpwater=4.187 kj/kg-candcpengine el=2.035 kj/kg·°c, oil . 120]