The law of universal gravitation states that a gravitational force exists between all objects in the universe. this force is directly proportional to the masses of the two objects and inversely proportional to the distance between them. this principle is a law because a. it is contradictory to ideas proposed by other scientists. b. it is subject to change as new technology and evidence emerges. c. it cannot be tested through a controlled scientific investigation. d. it has been demonstrated to be without exception under certain stated conditions.

D. It has been demonstrated to be without exception under certain stated conditions.

Explanation:

A principle is simply a proposition based on some results from some experiments. A principle becomes a law when it gains strength. That is when other scientists support and back it.

A scientific law is a statement that describes a natural phenomenon and is not contradicted by repeated experiments over the time.

Sir Isaac Newton's law of gravitation stated "A gravitational force exists between all objects in the universe. This force is directly proportional to the masses of the two objects and inversely proportional to the distance between them."

His law explained that every body in the universe attracts every other body. It explained that it is not just Earth that pulls us towards it. But even sun and moon has their own gravitational pull and so does all other objects. It is just that the Gravitational pull of some objects is negligible.

Newton's law of Gravitation is considered a universal law because it is applicable to almost all the bodies in the universe and is demonstrated to be correct for them under certain conditions.

answer; ///i believe that the correct answer is (45*) at a 45 degree check first good

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.