topic 5- forces

• What does a vector have that a scalar does not?

  Direction
• Why can scalars generally not be negative?

  They only have magnitude, no direction
• What is the scalar quantity for distance?

  Distance
• What is the vector quantity for displacement?

  Displacement
• What is the vector quantity for acceleration?

  Acceleration
• What is the scalar quantity for time?

  Time
• What is the vector quantity for force?

  Force
• What is the scalar quantity for mass?

  Mass
• What is the vector quantity for momentum?

  Momentum
• What is the scalar quantity for energy?

  Energy
• What is the displacement of a ball at the height of a cliff?


  0
• How is positive displacement defined for a ball thrown off a cliff?

  Above the cliff
• How is negative displacement defined for a ball thrown off a cliff?

  Below the clifftop
• How can you set the "0" point of a vector in a problem?

  By choosing a reference point
• When is speed considered velocity?

  When a direction is given
• What is the velocity of an object thrown at $10 \text{ m/s}$ at $30^\circ$?


  It is $10 \text{ m/s}$ with direction
• What happens to the velocity of a car traveling around a roundabout at constant speed?

  Its direction is constantly changing
• What does a vector represent visually?

  An arrow with size and direction
• What is a force?

  A push or pull on an object
• What are the two types of forces?

  Contact and non-contact forces
• How does gravitational attraction work?

  Mass creates a force of attraction
• What is weight?

  Force exerted on mass by gravity
• How is weight calculated?

  Weight = mass × gravitational field strength
• What is the formula for weight?

  W = mg
• What is the unit for weight?

  Newtons (N)
• How is mass measured?

  Using a force meter
• What is the value of gravitational field strength on Earth?

  9.8 N/kg
• How does weight change on different planets?

  Weight varies with gravitational field strength
• What is the acceleration in free fall due to gravity?

  It is equal to $g$
• Where does the weight of an object act?

  At the object's center of mass
• What is a resultant force?

  Sum of all forces acting on an object
• How is the resultant force calculated when forces act in the same direction?

  By adding the forces together
• How is the resultant force calculated when forces act in opposite directions?

  By subtracting the forces
• What forces act on a skydiver during free fall?

  Air resistance and weight
• What happens to the resultant force as a skydiver falls?

  It decreases as air resistance increases
• What is terminal velocity?

  When resultant force is zero
• What do free body diagrams show?

  Forces and their directions on an object
• How can a force at angle $\theta$ be resolved?


  Into parallel and perpendicular components
• What is the formula for work done?

  Work Done = Force × Distance
• What is the unit for work done?

  Joules (J)