When charged particles are separated by an infinite dis- tance, the electric potential energy of the pair is zero. When 19. 7. the particles are brought close, the electric potential energy of a pair with the same sign is positive, whereas the electric potential energy of a pair with opposite signs is negative. Give a physical explanation of this statement.

Explanation:

Potential energy Is given as.

U=kq1q2/r

Where k is a constant

q1 is charge

And q2 is also a charge

r is the distant between the two charges

When distance between the two charges is infinity then, the potential energy will b zero

U=kq1q2/∞

Therefore

U=0

Thus, the potential energy is zero when charged particles are separated by an infinite distance.

Let considered that both charges are positive.

Then U becomes

U=k(+q1)(+q2)/r

This shows that the energy is positive when the charges are positively charge. Also if the charges are also both negative charged the total energy will also be positive

U=k(-q1)(-q2)/r.

Both when their are opposite charges, the energy will be negative

U=k(-q1)(+q2)/r

U will be negative

-4 on

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.