SP9 - Forces and their Effects ✓ Flashcards Preview

Edexcel GCSE Physics COPY > SP9 - Forces and their Effects ✓ > Flashcards

Flashcards in SP9 - Forces and their Effects ✓ Deck (12)
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SP9a - What do you call forces between objects that are touching?

Contact forces


SP9a - What is the name for the regular upward force form the ground when you're standing?

Normal contact force


SP9a - What are the three non-contact forces?

  • Gravitational fields
  • Static electricity
  • Magnetism


SP9a - What do all objects that produce a non-contact forces have?

A force field.

An area around an object in which another object could experience a force.


SP9a - Describe how the gravitational pull between the earth and the moon are action-reaction forces.

  • Force is a vector quantity.
  • The force of the moon on the earth is the same size as the earth on the moon but they are in opposite directions.
  • Neither objects move in the direction of the force.


SP9c - What is the formula for a moment?

Moment (N m)


Force (N) x distance perpendicular to the pivot (m)


SP9c - What could you say when weights around a pivot are balanced?

It is in equilibrium


SP9c - What is the principle of moments?

The some of clockwise moments = the sum of anti-clockwise moments

[When a system is in equilibrium]


SP9b - How do you work out the direction and size of the resultant force using the component forces?

The Parallelogram method:

  • (If the start of a diagram hasn't already been provided, draw to the two forces using a scale)
  • Draw another pair of dashed-lines parallel to the forces
  • This should form a parallelogram
  • Draw a line from the object to the vertically opposite corner
  • Measure this line and use the scale to work out the size
  • If required, measure the angle to show the direction


SP9b - How do you resolve the component forces using the resultant force?

The Rectangle method:

  • Draw faint horizontal and vertical lines fom the object
  • Measure the angle from the horizontal/vertical that the object is at
  • Using a scale, draw a line the represent this force
  • Draw lines down and across from where this line ends to the horizontal and vertical respectively
  • Measure out the length from the object to each of these poitns
  • Use the scale to work out the size


SP9c - Explain why using two different sized gears in a car may be beneficial.

  • The first smaller gear can be connected to the motor
  • The second larger gear recieves the moment (turning force) from the first gear
  • Since the second gear is larger, it will have a larger radius.
  • This means that its moment will be greater (M = F x d)
  • Therefore it will transfer more turning force to the wheels of the car.


SP9c - Why is a longer lever more effective?

  • The formula for a moment (the turning force) is M = F x d
  • Thus, by increasing the distance form the pivot, you will either:
  1. Increase the turning force
  2. Decrease the force required to produce the same turning force