The moment of a force about a pivot is force × perpendicular distance, measured in newton metres, so this Year 9 sheet opens with the turning definition and its unit. Balance means clockwise moments equal anticlockwise ones in the key.
Key Takeaways
Moment = force × perpendicular distance from the pivot (Q1).
The unit of a moment is the newton metre (Q2).
Q3 records the balance of clockwise and anticlockwise moments.
Section A: Multiple Choice Questions (1 Mark Each)
Choose the correct option for each question.
1.The moment of a force about a pivot is
(a) force × perpendicular distance from the pivot(b) force ÷ distance(c) mass × distance(d) force + distance
2.The unit of a moment is the
(a) newton metre(b) newton(c) metre(d) joule
3.For an object to be balanced, the principle of moments states that
(a) the sum of clockwise moments equals the sum of anticlockwise moments(b) clockwise moments are always bigger(c) there are no moments(d) all the forces are equal
4.A lever is a simple machine that works on the principle of
(a) moments(b) pulleys(c) screws(d) gears
5.Increasing the distance of a force from the pivot
(a) increases the moment(b) decreases the moment(c) has no effect on the moment(d) reverses the moment
6.A see-saw is balanced with a heavier person on one side. For it to stay balanced, the heavier person must
(a) sit closer to the pivot than the lighter person(b) sit further from the pivot(c) sit at the very end(d) nothing can balance it
Section B: Short Answer Type Questions (2 Marks Each)
Show all steps clearly.
7.Define the moment of a force.
8.Write the formula for the moment of a force.
9.State the principle of moments.
10.What is a pivot?
11.Give one example of a lever used in everyday life.
12.How can you double the moment of a force without changing the size of the force?
13.What happens to the moment when the force is doubled at the same distance from the pivot?
14.What unit is used to measure a moment?
Section C: Numericals & Word Problems (3 Marks Each)
Apply the concepts to solve the problems. Show all working.
15.A force of 20 N acts at a distance of 0.5 m from a pivot. Using moment = F × d, find the moment.
16.A force of 15 N acts at a distance of 2 m from a pivot. Using moment = F × d, find the moment.
17.A moment of 40 Nm is produced by a force of 10 N. Using d = moment ÷ F, find the distance from the pivot.
18.A see-saw is balanced. A child of weight 300 N sits 2 m from the pivot. Using the principle of moments, find the distance needed for a child of weight 200 N on the other side.
19.A force of 25 N produces a moment of 75 Nm. Using d = moment ÷ F, find the distance from the pivot.
20.A spanner is 0.3 m long. A force of 40 N is applied at its end. Using moment = F × d, find the moment.
Answer Key
1. a) force × perpendicular distance from the pivot
2. a) newton metre
3. a) the sum of clockwise moments equals the sum of anticlockwise moments
4. a) moments
5. a) increases the moment
6. a) sit closer to the pivot than the lighter person
7. Refer to solution guide.
8. Refer to solution guide.
9. Refer to solution guide.
10. Refer to solution guide.
11. Refer to solution guide.
12. Refer to solution guide.
13. Refer to solution guide.
14. Refer to solution guide.
15. Refer to solution guide.
16. Refer to solution guide.
17. Refer to solution guide.
18. Refer to solution guide.
19. Refer to solution guide.
20. Refer to solution guide.
End of Worksheet
People Also Ask
What is the moment of a force about a pivot?
Force × perpendicular distance from the pivot, option (a) in this worksheet (Q1).
What is the unit of a moment?
The newton metre, option (a) in this worksheet (Q2).
When is a lever balanced?
When clockwise moments equal anticlockwise moments, option (a) in this worksheet (Q3).
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