Q1. A passenger train is travelling at 31 m/s when the engineer sees a freight train 351 m ahead of his train travelling in the same direction on the same track. The freight train is moving at a speed of 5.6 m/s.

(a)If the reaction time of the engineer is 0.39 s, what is the minimum (constant) rate at which the passenger train must lose speed if a collision is to be avoided?

(b) If the engineer's reaction time is 0.81 s and the train loses speed at the minimum rate described in Part (a), at what rate is passenger train approaching the freight train when the two collide?

(c) For both reaction times, how far will the passenger train have travelled in the time between the sighting of the freight train and collision?

Q2. Two particles are fixed to an x axis: particle 1 of charge q1 = 2.69 x 10-8 C at x = 29.6 cm and particle two of charge q2 = -5.20 q1 at x = 63.5 cm. At what coordinate on x axis is the electric field produced by the particles equal to zero?