Question

A particle of mass 40 µg and carrying a charge 5 × 10^–9 C is moving directly towards fixed positive point charge of magnitude 10^–8 C. When it is at a distance of 10 cm from the fixed point charge it has a velocity of 50 cm/s. At what distance from the fixed point charge will the particle come momentarily to rest ? Is the acceleration constant during motion ? 

Answer 1

If the particle comes to rest momentarily at a distance r from the fixed charge, then from 'conservation of energy' we have

i.e., acceleration is not constant during motion.