The figure above shows two positively charged particles. The +Q charge is fixed in position, and the +q charge is brought close to +Q and released from rest. Which of the following graphs best depicts the acceleration (a) of the +q charge as a function of its distance (r) from +Q?
Doubt by Arshia
Solution :
Suppose the distance between the two charge at any instant is r. When the charge +q is brought close to charge +Q then it will experience a columbic force of repulsion which is given by coulomb's law
F= kQq/r²
ma = kQq/r² [∵F=ma]
a=kQq/ar²
a∝1/r² [∵k,Q,q and a are constants]
F= kQq/r²
ma = kQq/r² [∵F=ma]
a=kQq/ar²
a∝1/r² [∵k,Q,q and a are constants]
Clearly, acceleration is inversely proportional to the distance r between the two charges at any instant.
Hence, graph depicted in a) would be the correct option.
