Exam-style question
Try this first
A particle of mass 3 kg has resultant force 15 N. Find the acceleration.
- A.5 m s^-2
- B.8
- C.2
- D.10
Model answer
What a good answer should say
- The correct answer is 5 m s^-2.
This answer is tied to the objective: R4 Understand and use Newton's third law; use equilibrium of forces on a particle and motion in a straight line, restricted to forces in two perpendicular directions or simple two-dimensional vector cases; apply to smooth pulleys and connected particles; resolve forces in two dimensions; use equilibrium of a particle under coplanar forces..
Explanation
Why this works
Use the explanation to connect the worked answer back to R4 Understand and use Newton's third law; use equilibrium of forces on a particle and motion in a straight line, restricted to forces in two perpendicular directions or simple two-dimensional vector cases; apply to smooth pulleys and connected particles; resolve forces in two dimensions; use equilibrium of a particle under coplanar forces..
The distractors change the result or the form of the answer. The canonical solution reaches 5 m s^-2, so 5 m s^-2 is the only option consistent with the working.
Maths method check
- Topic focus: Mechanics.
- Question style: practice.
- Reasoning demand: application.
- Check the operation, notation, units, and final answer form against the question before moving on.
Common mistake
No common mistake is linked to this question yet.