(Constant Acceleration and the Equations of Kinematics, Free-Fall) 4. (15 pts total + Extra Credit) As shown in Figure 2, particle A is thrown directly downward at initial velocity of magnitude 100.0 m/s from a height of 500.0 m above ground level. At the same time, particle B is dropped from rest from a height of 200.0 m above ground level. O particle A 100.0 m/s 500.0 m O particle B 200.0 m ground level Figure 2. A particle A fired downward as a second particle B is simultaneously dropped from rest. a. (15 pts) Determine at what time after their release the particles will pass each other by. Make sure to follow all the steps of solving a physics problem including setting up an appropriate coordinate system, introducing the required variables and solving the problem algebraically first. You may make use of Figure 2 itself to set up the coordinate system and define your viables. Treat the problem as free-fall and express your answer in units of meters. Let g = 9.8 m/s' exactly, if needed