# Y9 forces

The flashcards below were created by user AHutson on FreezingBlue Flashcards.

1. What is a moment?
The turning effect of a force
2. How are moments calculated?
Moment (Nm) = Force (N) x distance from pivot (m)
3. What is a pivot?
The point around which something turns
4. What is fulcrum an alternative word for?
Pivot
5. What is a lever?
Something that uses moments to make a task require less force (make it easier)
6. Name some examples of levers
• Can opener
• Scissors (especially nail scissors)
• Wheel barrow
• Crowbar
• Wheel spanner
7. What do we know about the anti-clockwise moment and the clock wise moment if an object is not turning?
They are balanced
8. What are the units for force?
Newtons (N)
9. What are the units of distance?
Metres (m)
10. What are the units of moments?
Newton metres (Nm)
11. What is a pendulum?
An object that swings to and fro
12. What affects the time that a pendulum takes to make a complete swing?
The length of the pendulum (nothing else!)
13. What name we give to the time for a pendulum to make a complete swing (back to its starting place)?
Time Period
14. What unit is used to measure time?
second (s)
15. What unit is used to measure speed?
Metres per second (m/s)
16. What unit is used to measure acceleration?
Metres per second squared

17. What is the equation for calculating acceleration?
change in speed / time taken
18. Name the force that keeps objects moving in a circle
Centripetal force
19. In which direction does centripetal force act?
Towards the centre of the circle
20. What is the unit of centripetal force?
Newtons (N)
21. What three things affect the size of the centripetal force needed to keep an object moving in a circle?
• Speed of the object
• Mass of the object
22. Does increased speed need a larger or smaller centripetal force?
Larger
23. If the radius of the circle increases, what effect does this have on the centripetal force needed?
It reduces
24. If the mass of the object increases, what effect does this have on the centripetal force needed?
Increases
25. What provides the centripetal force that keeps the Earth orbiting around the Sun?
Gravity
26. What provides the centripetal force that keeps a conker tied to a piece of string moving in a circle
The tension in the string
27. In which direction does air resistance act?
Opposite to the direction of travel
28. If the speed of an object increases, how does this affect the air resistance?
Air resistance increases
29. If forces are balanced what do we know about the speed of an object?
• It moves at a constant speed.
• (If it was not moving it stays not moving)
30. What is terminal velocity?
• The speed an object moves at when the forces acting on it are balanced.
• eg a skydiver falling when her weight and air resistance are equal
31. Why does opening a parachute increase air resistance?
The parachute has a large surface area
32. What are the two units of pressure?
or Pascals (Pa)
33. What is the equation to calculate pressure?
34. What are the units for Area ?
35. What is inertia a measure of?
How hard to start or stop something moving
36. What two things affect the inertia of an object?
• Mass
• Speed
37. When a skydiver is falling, does her weight or air resistance change as her speed changes?
Air resistance (Her weight is constant)
 Author: AHutson ID: 244293 Card Set: Y9 forces Updated: 2013-11-01 10:48:10 Tags: Y9 forces Folders: Description: Y9 forces Show Answers: