a particle of mass 2g and charge 1 microCoulomb is held at rest on a frictionless surface at a distance of 1m from a fixed charge of 1mC . if the particle is released it will be replled . the speed of the particle when it is at a distance of 10 m from the fixed charge is :
1. 100 m/s
2. 90 m/s
3. 60 m/s
4. 45 m/s
ans. is : 2.) 90 m/s
plz.. explain how
Answers
mass of particle, m = 2g = 2 × 10^-3 kg
charge on particle , q = 10^-6 C
another charged particle Q = 1mC = 10^-3C is fixed at r = 1m from first particle.
repulsion force acts between particles , F = kqQ/r²
= 9 × 10^9 × 10^-3 × 10^-6/1²
= 9N
from Newton's 2nd law, Acceleration of first particle , a = F/m
= 9/2 × 10^-3 = 9000/2 = 450 m/s²
Let final velocity of particle is v m/s
initial velocity of article is 0 m/s
displacement covered by particle = final position - initial position
= 10m - 1m = 9m
using formula, v² = u² + 2as
or, v² = 0 + 2 × 450 × 9
or, v² = 8100 = 90² => v = 90 m/s
hence, velocity of particle it is at a distance of 10 m from the fixed charge is 90m/s
Answer:
⚡answer as per question should be 284.6m/s.
steps in attachment..... inorder to get 90m/s then mass given in question has to be 20g not 2g⚡
