Forces And Motion

• What is a force?

  A push or pull
• What are contact forces?

  Forces when objects are physically touching
• What are non-contact forces?

  Forces like magnetism and gravity
• What is the role of electrostatic repulsion in contact forces?

  It causes contact forces like pushing a door
• What is a normal contact force?

  The force when pushing a door
• What are examples of contact forces?

  Friction, air resistance, and tension
• How can forces be represented?

  With vectors showing direction and magnitude
• What does the length of a force vector indicate?

  The magnitude of the force
• What is a resultant force?

  The total force acting on an object
• How do you find the resultant force when forces act in opposite directions?

  Add the vectors, making one negative
• If the resultant force is 3 Newtons to the right, what does that indicate?

  Positive direction is to the right
• What do you use to find the resultant force if vectors are at right angles?


  Pythagoras' theorem
• What is the equation for calculating the resultant force?

  $F_{resultant} =$$\sqrt{F_1^2 + F_2^2}$
• What does it mean if forces are balanced?

  They add up to zero
• What is Newton's first law of motion?

  An object will not change velocity without a resultant force
• What is a scalar quantity?

  A quantity with magnitude only
• What is the difference between displacement and distance?

  Displacement includes direction
• How is weight calculated?

  Mass times gravitational field strength
• What is the gravitational field strength on Earth?

  Approximately $9.8 \text{ N/kg}$
• What is the weight of a 1 kg mass on Earth?

  10 Newtons
• What must you do to lift an object at constant speed?

  Apply a force equal to its weight
• What is the equation for work done?

  Work done equals force times distance
• How do you calculate gravitational potential energy gained?

  $m \cdot g \cdot h$
• What does Hooke's law state?

  Force equals spring constant times extension
• What is the unit for spring constant?

  Newtons per meter
• What happens to an object that stretches elastically?

  It returns to its original shape
• What does it mean if force and extension are directly proportional?

  Doubling one doubles the other
• What should you ensure when measuring extension of a spring?

  Zero mark is lined up with the bottom
• What is a systematic error?

  An error due to consistent measurement issues
• What is a random error?

  An error that varies unpredictably
• What is the energy stored in a spring?

  Half the spring constant times extension squared
• What is the equation for torque (moment)?

  Torque equals force times distance to pivot
• What happens when moments are balanced?

  The object will not turn
• What is the principle of moments?

  Moments turning clockwise equal moments anticlockwise
• What is pressure?

  Force divided by area
• What is the unit for pressure?

  Newtons per square meter or Pascals
• Why does pressure increase underwater?

  Due to the weight of water above
• What is the equation for calculating pressure in a fluid?

  $P =$$H \cdot \rho \cdot g$
• What is the density of water?

  1,000 kg per cubic meter
• What causes gas pressure?

  Collisions of gas particles with surfaces