The following statements are observations made about a towing vehicle and a bus that is being towed I. The…

Analyze the question: We need to decide which statements about the towing vehicle and the towed bus are correct. This is a Newton's Third Law question (action and reaction) combined with ideas about forces on a moving body.

Concept:

• Newton's Third Law: if body A exerts a force on body B, then B exerts an equal and opposite force on A. These two forces act on different bodies and are always equal in magnitude, whether the bodies are accelerating or not.
• Forces from different interactions (e.g. tow-bar force and road friction) are not action-reaction pairs. They are equal only in special cases, such as constant velocity.

Checking each statement:

• I. The tow force on the bus is compared with the force the bus exerts on the road. These are different interactions (vehicle-bus vs bus-road), so they are not a Third Law pair. They are equal only if the bus moves at constant velocity with no other forces. This is not guaranteed, so I is not necessarily correct.
• II. The force of the towing vehicle on the bus and the force of the bus on the towing vehicle are a genuine action-reaction pair. They are always equal in magnitude, so II is correct.
• III. This says the forces are unequal, which contradicts Newton's Third Law. III is false.
• IV. The force the road exerts on the towing vehicle (the driving friction) is not a Third Law partner of the tow force. It is larger than the tow force when the system accelerates, because it must also move the towing vehicle itself. So IV is not necessarily correct.

Conclusion: Only statement II is always true.

Answer: B (II only)

Tip: For Third Law questions, ask, "Are these two forces between the same two objects?" If yes, they are equal and opposite. If a third object (like the road) is involved, they are not a Third Law pair.