forces

• Momentum = Mass x Velocity
• Vectors - have a magnitude and direction. velocity, acceleration, displacement, force
• Scalars - only have a magnitude. speed, distance, time, mass
• Distance-Time Graphs

  • The steeper the gradient, the faster the speed
  • a horizontal line indicates that the object is stationary.
  • a steepening curve means accelerating.
  • a leveling off curve means decelerating

  A) time

  B) distance

  C) steady speed

  D) stationary

  E) decelerating

  F) accelerating

  
• Velocity-Time Graphs

  • The steeper the gradient, the greater the acceleration.
  • A negative gradient indicates that the object is decelerating.
  • a horizontal line indicates that the velocity is steady.
  • a curve is increasing acceleration/deceleration.
  • a straight uphill is constant acceleration.
  • a straight downhill is constant deceleration.

  A) time

  B) velocity

  C) steady velocity

  D) increasing acceleration

  E) steady velocity

  F) constant acceleration

  G) constant deceleration

  
• average speed = total distance / total time
• Newton's First Law - an object has constant velocity unless a resultant force acts upon it. If there is a resultant force, the object will accelerate
• Newton's 2nd Law - a non-zero resultant force causes acceleration.

  F = m x a

  force (N) = mass (kg) x acceleration (m/s2)
• Inertia is a measure of how difficult it is to change the velocity of an object (depending on its mass).
• Newton's 3rd Law - every action force has an equal and opposite reaction force.
• force in terms of momentum

  force = change in momentum / time
• force in terms of momentum

  F = p/t
• work done


  when a force makes an object, energy transferred and work is done
• work done

  work done (J) = force (N) x distance (m)
• work done


  W = F x d
• power


  power is the rate at which the energy is transferred
• power

  power (W) = work done (J) / time (s)
• power

  P = W/t
• elastic deformation - when a material goes back into its original shape after being stretched or compressed, when the force is removed.
• plastic deformation - when the material doesn't go back to its original shape after the force is removed
• the relationship between the extension of a spring and the force is called Hooke's Law.
• the maximum force that can be applied before the material starts deforming plastically is called the elastic limit
• spring extension = extended length - original length
• describe how to change the shape of an object

  two or more forces are needed, which are acting in different directions.
• elastic deformation: returns to its original shape after the force is removed
• moments are a turning effect
• principle of moments


  total anticlockwise movements = total clockwise movements
• moment (N / m) = force x perpendicular distance

  m = fd
• pivot: the centre
• What does Newton's first law of motion state?

  Objects remain at rest or constant velocity unless acted on
• What happens if the resultant force acting on an object is zero?

  The object remains stationary or moves uniformly
• If an object is stationary, what will happen if the resultant force is zero?

  The object will remain stationary
• If an object is moving with a constant velocity, what will happen if the resultant force is zero?

  The object will continue moving at the same velocity
• What can happen when the resultant force is not zero?

  The speed or direction of the object can change
• What does Newton's first law explain about uniform velocity?

  It explains why things move with constant velocity
• What does it mean if the forces acting on an object are balanced?

  The resultant force is zero
• When can the velocity of an object change according to Newton's first law?

  When a resultant force acts on the object
• What are the implications of Newton's first law of motion?

  • Objects at rest stay at rest
  • Objects in motion stay in motion
  • Change in motion requires a resultant force
• What does Newton's second law explain?

  Principles of force and acceleration
• How does an object respond to a resultant force according to Newton's second law?

  It accelerates, changing its velocity