How do you define the principal focus of a diverging lens? A. The place where incident rays parallel to the principal axis converge after they are refracted

B. The place where incident rays appear to have emanated from

C. The place where refracted rays parallel to the principal axis converge after they are refracted

D. The place where refracted rays appear to have emanated from

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.