Exam-style question
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Which statement best describes the relationship between the torque equation τ = r × F and the linear equation F = ma?.
- A.Torque is the product of force and distance, whereas F = ma relates force to mass and acceleration.
- B.Torque is a vector quantity, while F = ma is a scalar equation.
- C.The torque equation uses a lever arm, whereas F = ma does not involve any distance.
- D.Both equations describe the same physical quantity but in different units.
Model answer
What a good answer should say
- Torque is the product of force and distance, whereas F = ma relates force to mass and acceleration.
Explanation
Why this works
Define both: torque (τ) is the turning effect of a force applied at a distance (lever arm) from the axis, calculated as τ = r × F; F = ma is Newton’s second law relating linear force to mass and linear acceleration. Identify key difference: torque incorporates a distance (lever arm) and direction perpendicular to the force, whereas F = ma does not involve distance and applies to linear motion.
Explain when each applies: use τ = r × F when analysing rotational effects of forces about an axis; use F = ma when analysing linear motion of a body. Conclude: the correct statement highlights that torque involves a lever arm while F = ma does not, matching the question’s comparison requirement.
Common mistake
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