Newton's 3rd law and Free Body Diagrams

The two forces in each pair can act on the same object or on different objects.

False

The two forces in each pair may have different physical origins (for instance, one of the forces could be due to gravity, and its pair force could be a normal contact force).

False

Given that two objects interact via some force, the accelerations of these two objects have the same magnitude but opposite directions. (Assume no other forces act on either object.)

False

An object is hanging by a string from the ceiling of an elevator. The elevator is moving upward with a constant speed. What is the magnitude of the tension in the string?

The magnitude of the tension in the string is equal to the magnitude of the weight of the object.

A large truck collides head-on with a small car. The car is severely damaged as a result of the collision. According to Newton's third law, how do the forces acting between the truck and car compare during the collision?

The force on the truck is equal to the force on the car.

An object is hanging by a string from the ceiling of an elevator. The elevator is slowing down while moving upward. What is the magnitude of the tension in the string?

The magnitude of the tension in the string is less than the magnitude of the weight of the object.

Every force has one and only one 3rd law pair force.

True

The two forces in each pair act in opposite directions.

True

The two forces of a 3rd law pair always act on different objects.

True

According to Newton's 3rd law, the force on the (smaller) moon due to the (larger) earth is

equal in magnitude to, and in the opposite direction from, the force on the earth due to the moon.

An object is at rest on a tabletop. Earth pulls downward on this object with a force equal in magnitude to mg. If this force serves as the action force, what is the reaction force in the action-reaction pair?

the object pulling upward on Earth