A particle with a charge of 34 C and a mass of 27 x 106 kg i

A particle with a charge of -3.4 C and a mass of 2.7 x 10-6 kg is released from rest at point A and accelerates toward point B, arriving there with a speed of 83 m/s. The only force acting on the particle is the electric force. What is the potential difference VB - VA between A and B? If VB is greater than VA, then give the answer as a positive number. If VB is less than VA, then give the answer as a negative number.

Solution

force on particle is from A to B.

then field is B to A.

field is always from higher potential to lower potential.

so Vb - Va > 0

and change in PE = qdeltaV

mv^2 /2 = q (Va - Vb)

2.7 x 10^-6 x 83^2 /2 = 3.4 x 10^-6 x (Vb - Va)

Vb - Va = 2735.34 Volt