AP · AP C:M · multiple choice
AP Physics C: Mechanics · Question 3
AP Physics C: Mechanics · Original GioPhysics question with a detailed, mark-by-mark answer guide.
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multiple choice1 mark
A single force F(x) = 4x² acts on an object as it moves along the x-axis, where F is in newtons and x in metres. How much work does this force do on the object as it moves from x = 0 to x = 3.0 m?
- A
12 J
- B
36 J
- C
54 J
- D
108 J
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Answer overviewCorrect answer: B — 36 J
01
1 markAnswer and reasoning
How to approach it
Predict from the governing principle before looking for a matching option. Then reject alternatives by checking direction, units, limiting behaviour or the physical meaning of each statement.
- 1
The correct choice is B: 36 J
- 2
D is F(3.0) × 3.0 = 108 J, the answer of a candidate who multiplies the final force by the distance instead of integrating. Since the force varies, the work is ∫₀³ 4x² dx = (4/3)(27) = 36 J.
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