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Difficulty: MediumNewton's Third Law (Action/Reaction)

Evaluate the accuracy of the following claim: During a head-on collision between a heavy commercial transport truck and a lightweight passenger car, the impact force that the truck exerts on the car is greater in magnitude than the force that the car exerts on the truck.

Answer: Answer

Answer

The claim is false. The forces exerted by the two vehicles upon each other are identical in magnitude.
The statement is false because Newton's Third Law of Motion dictates that any two interacting bodies exert equal and opposite forces upon one another. Even though the truck possesses a much larger mass, the actual force of impact it applies to the car is exactly the same magnitude as the force the car applies to the truck.

Step-by-Step Solution

1
Identify the two interacting objects and the physical law governing their interaction.
The objects are the heavy truck and the lightweight car. The mutual interaction is governed by Newton's Third Law of Motion (action and reaction).
Determining the correct physical principle is necessary to evaluate the relationship between the forces during the collision.
2
Apply Newton's Third Law to the collision scenario.
The law states that for every action force, there is an equal and opposite reaction force. Therefore, the force the truck exerts on the car must be identical in magnitude to the force the car exerts on the truck.
This direct application of the law disproves the claim made in the question stem.
3
Differentiate between the applied force and the resulting acceleration to avoid common misconceptions.
While the impact forces are exactly equal, the car experiences a significantly greater acceleration (and consequently more structural damage) because its mass is much smaller (a=Fma = \frac{F}{m}).
Clarifying why the car suffers more damage confirms that the unequal effects are due to mass differences under Newton's Second Law, not unequal forces.

Key Concept

Newton's Third Law states that all forces exist in pairs, and whenever two objects interact, they exert forces upon each other that are equal in magnitude and opposite in direction.

Alternative Method

You can logically verify this by considering Newton's Second Law combined with the Third Law. The perfectly equal forces cause different accelerations inversely proportional to the masses (a=Fma = \frac{F}{m}). The car's massive acceleration often misleads observers into incorrectly assuming the force applied to it was larger.
Estimated Time:45s
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Newton's Third Law (Action/Reaction)

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