A star with the same mass and diameter as the sun rotates about a central axis with a period of about [06] days. Suppose that the sun runs out of nuclear fuel and collapses to form a white dwarf star with a diameter equal to that of the earth. Assume the star acts like a solid sphere and that there is no loss of mass in the process. and that the star has no external torques acting on it. Note however, that as the star cools and gravity causes it to contract, its rotational kinetic energy changes. What is the ratio of final to initial kinetic energies (Kf/Ki)?

yup its correct its: c) b b

causes

fossil fuels burn

cities become more industrialized

human population grows worldwide

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.

the right answer is 0.3 meters per second