forces

• what are the two types of forces?

  contact and non-contact
• what is a force?


  A force is a push or pull that can cause an object to move, stop, or change direction or shape.
• what is the unit for measuring forces?


  Newton
• when are contact forces exerted?


  When objects physically touch each other.
• what do we use to show forces?


  arrows
• what is weight?


  the force of gravity pulling on you
• what is mass?

  Mass is a measure of the amount of matter in an object.
• weight/mass = gravitational field strength
• what can materials do?


  they can stretch and compress
• what is the extension of a spring?


  the difference between the original and stretched length
• what is hooke's law?

  the extension of the spring is proportional to the force up to a certain point
• does hooke's law apply to all materials?

  no
• what is an elastic limit?

  when a spring has enough force applied to it and it can no longer return to it's original length
• what can be used to measure force?

  Force meters(they have a spring inside it that will stretch when force is applied)
• what is frictional force?

  the force that opposes motion between 2 objects in contact
• how is friction useful?

  it helps us walk and write
• how do you reduce friction?

  Lubrication, making surfaces smoother
• what are the disadvantages of friction?

  Wear down machines, causes things to overheat
• what is pressure?

  Force per unit area.
• what is the formula for pressure?

  Pressure = Force/Area
• what is the SI unit for pressure?

  Pascal
• what is newton's first law of motion?

  Inertia -> objects stay at rest and an object in motion stays in motion with the same speed and direction unless acted up by an unbalanced force
• what are balanced forces?

  Equal forces acting on an object in opposite directions.
• forces have a magnitude and direction
• what are unbalanced forces?

  2 forces acting against each other but one is bigger than the other
• how can unbalanced forces affect a moving object?

  change its speed or direction, stop the object
• what type of forces are acting on stationary objects?

  Balanced forces
• every object changes shape when a force acts on it but the movement is mostly too small to see