Newton's Laws - Mission NL12 Detailed Help

The Earth is held in orbit by the force of gravity between the Earth and the more massive Sun. The force of the Earth on the Sun is ____ the force of the Sun on the Earth; the resulting acceleration of the Earth is ____ the acceleration of the Sun.

Newton's Third Law:
For every action there is an equal and opposite reaction.

Newton's Second Law:
The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.

This question involves a dual application of Newton's second and third laws (stated above). You are asked to compare the magnitude of the forces exerted between Earth and Sun (a third law question) and the magnitude of the resulting accelerations of the Earth and a Sun (a second law question).

According to the third law, forces between two interacting objects occur in equal and opposite pairs. The Earth and the Sun pull upon each other with equal and opposite forces. According to the second law, the resulting accelerations will depend directly upon the force and inversely upon the mass. Since both Earth and Sun encounter equal forces, it is the mass of the objects which will make their accelerations different. The least massive object has the greater acceleration.


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