Science 8 · Unit 3: Forces and energy · Cambridge Lower Secondary Science Stage 8

Questions

1. 1. What is the turning effect of a force called?

   • a moment
   • a pressure
   • a revolution
   • a minute
   Check

2. 2. Which action needs a turning force?

   • stretching an elastic band
   • twisting the top off a bottle
   • pushing a trolley up a ramp
   • pulling a chair across the floor
   Check

3. 3. What is the equation for a moment?

   • moment = force × distance from the pivot
   • moment = force ÷ area
   • moment = force ÷ distance
   • moment = mass × speed
   Check

4. 4. What is the unit of a moment?

   • kg
   • N m (newton metres)
   • N/m²
   • m/s
   Check

5. 5. A crane holds a 15 000 N weight 5 m from its pivot. What is the moment?

   • 75 N m
   • 15 005 N m
   • 75 000 N m
   • 3000 N m
   Check

6. 6. The weight on the crane is moved further from the pivot. What happens to the moment?

   • It stays the same.
   • It becomes zero.
   • It decreases.
   • It increases.
   Check

7. 7. A nut needs a moment of 40 N m. The spanner is 0.2 m long. What force is needed?

   • 8 N
   • 20 N
   • 40.2 N
   • 200 N
   Check

8. 8. Why is a longer spanner easier to use?

   • It makes the nut smaller.
   • It reduces the moment.
   • A longer distance gives a bigger moment for the same force.
   • It is lighter.
   Check

9. 9. An engine exerts 350 N m on a wheel of radius 0.35 m. What is the force at the edge?

   • 100 N
   • 350 N
   • 122.5 N
   • 1000 N
   Check

10. 10. Sofia weighs 500 N and sits 2 m from a seesaw's pivot. What moment does she exert?

    • 250 N m
    • 100 N m
    • 502 N m
    • 1000 N m
    Check

11. 11. Zara weighs 400 N. How far from the pivot must she sit to balance Sofia's 1000 N m?

    • 2.5 m
    • 0.4 m
    • 4 m
    • 2 m
    Check

12. 12. When does a seesaw balance?

    • when the moments on both sides are equal
    • when no one sits on it
    • when one side is longer
    • when both people weigh the same only
    Check

13. 13. What is the point a lever turns around called?

    • the load
    • the pivot
    • the moment
    • the effort
    Check

14. 14. Why is a door handle placed far from the hinges?

    • to reduce the moment
    • to make the door heavier
    • to give a bigger moment so the door opens easily
    • to make it look nice
    Check

15. 15. If force is in pounds and distance in feet, what is the unit of moment?

    • feet per pound
    • pound feet
    • square feet
    • pounds per foot
    Check

16. 16. A pull of 35 N opens a door. The handle is 0.8 m from the hinges. What is the moment?

    • 35.8 N m
    • 34.2 N m
    • 28 N m
    • 43.75 N m
    Check

17. 17. Zara (450 N) sits 1.5 m from a seesaw's pivot. Where must Sofia (500 N) sit on the other side to balance it?

    • 3 m from the pivot
    • 1.67 m from the pivot
    • 1.5 m from the pivot
    • 1.35 m from the pivot
    Check

18. 18. A brake lever needs a moment of 1.8 N m. The force is applied 0.12 m from the pivot. What force is needed?

    • 1.5 N
    • 15 N
    • 150 N
    • 0.216 N
    Check