02_P71InstructorSolution

02_P71InstructorSolution - 2.71. Model: equations....

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
2.71. Model: Treat the car and train in the particle model and use the constant acceleration kinematics equations. Visualize: Solve: In the particle model the car and train have no physical size, so the car has to reach the crossing at an infinitesimally sooner time than the train. Crossing at the same time corresponds to the minimum 1 a necessary to avoid a collision. So the problem is to find 1 a such that 2 45 x = m when 2 60 y = m. The time it takes the train to reach the intersection can be found by considering its known constant velocity. 20 02 2 2 60 m 30 m/s 2.0 s yy vv t tt t == = = = Now find the distance traveled by the car during the reaction time of the driver.
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.
Ask a homework question - tutors are online