A student in St. Lucia sets up an experiment with a metre rule balanced on a knife edge at the 50 cm mark. She hangs a 2.0 N weight at the 20 cm mark. At which mark should she hang a 3.0 N weight to balance the rule?

Q: How do I try a free CXC Physics question?

Just tap any of the four options on this page — no signup, no card, nothing to install. You'll see the correct answer and a full mark-scheme-style explanation within a second. Each visit shows a fresh randomly-picked question from the live CXC CSEC Physics bank, so you can keep refreshing to try different ones before deciding whether to create a free account for daily access.

Q: Is Kramizo really free for CXC Physics students?

Yes — completely free. Every student gets 45 questions a day on the free plan, across any board and any subject, with no card required and no trial countdown. Kramizo's optional Pro plan removes the daily cap and adds analytics, but the free plan is genuinely free forever. We make money from the small percentage of students who choose to upgrade — not from selling data or ads.

Q: Are the Physics questions aligned to the CXC CSEC syllabus?

Every question is written against the published CXC CSEC Physics syllabus and reviewed for accuracy before being added to the bank. We match the command words (state, describe, explain, evaluate), mark allocations, and difficulty tier you'll see on real CXC past papers. Explanations are written in the style of official examiner mark schemes so students learn exactly what marks are being awarded for.

Question

A student in St. Lucia sets up an experiment with a metre rule balanced on a knife edge at the 50 cm mark. She hangs a 2.0 N weight at the 20 cm mark. At which mark should she hang a 3.0 N weight to balance the rule?

Accepted Answer

70 cm — Award 1 mark for correct application of principle of moments. Taking moments about the 50 cm mark: clockwise moment = 2.0 N × 30 cm = 60 N cm. For balance, anticlockwise moment must also equal 60 N cm. If 3.0 N weight is at distance d from pivot: 3.0 × d = 60, so d = 20 cm. Position = 50 + 20 = 70 cm. A is incorrect — gives only 10 cm distance. B is incorrect — gives 15 cm distance. D is incorrect — gives 25 cm distance.

Answer

70 cm

Answer

60 cm

Answer

75 cm

Answer

65 cm

One real Physics question.No signup. 30 seconds.

One real Physics question.
No signup. 30 seconds.