topic 5 forces

• What is a vector defined by?

  A vector has magnitude and direction
• What does a scalar have?

  A scalar has just magnitude
• Can scalars be negative?

  No, scalars cannot be negative
• Can vectors be negative?

  Yes, vectors can be negative
• What are examples of scalars and vectors?

  • Scalars: Speed, Distance, Time, Mass, Energy
  • Vectors: Velocity, Displacement, Acceleration, Force, Momentum
• What is the displacement of a ball at the height of a cliff?

  The displacement is 0 at the cliff height
• How is displacement defined above and below the cliff?

  Positive above, negative below the cliff
• What is the significance of the "0" point in vector questions?

  You can set the "0" point arbitrarily
• When is speed considered velocity?

  When direction is specified
• What happens to a car's velocity when it travels around a roundabout?

  The velocity is constantly changing
• How can vectors be visually represented?

  By arrows indicating magnitude and direction
• What is a force?

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

  • Non-Contact Forces: Electrostatic, Gravitational
  • Contact Forces: Normal contact force, Friction
• What does gravitational attraction depend on?

  It depends on mass
• What is weight defined as?

  The force exerted on a mass by gravity
• How is weight calculated?

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

  W = mg
• What is the gravitational field strength on Earth?

  g = 9.8
• How does weight differ on different planets?

  Weight varies due to different gravitational strengths
• What is the acceleration in free fall due to gravity?

  It is the same as g, i.e., $10 \, \text{m/s}^2$
• Where does the weight of an object act?

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

  A single force representing all acting forces
• How do you find the resultant force when forces act in the same direction?

  Add the forces together
• How do you find the resultant force when forces act in opposite directions?

  Subtract the smaller force from the larger
• What forces act on a skydiver?

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

  The resultant force decreases as air resistance increases
• What occurs when the resultant force is zero?

  There is no acceleration, and terminal velocity is reached
• What do free body diagrams represent?

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


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

  Work Done = Force × Distance
• What are the units for work done?

  Joules (J)
• When is work done against gravity?

  When moving an object vertically
• What is one joule of work defined as?

  One newton causing one metre displacement
• What happens when work is done against friction?

  It causes a rise in temperature of the object
• What is deformation?

  Changing the shape of an object
• What are the types of deformation?

  • Elastic Deformation: Returns to original shape
  • Plastic Deformation: Does not return to original shape
• What does Hooke's Law state?

  Extension is directly proportional to force applied
• What is the formula for Hooke's Law?

  F = ke
• What does a linear line on a Force/Extension graph indicate?

  It indicates elastic behavior following Hooke's Law

  
• What happens at the limit of proportionality?

  It stops obeying Hooke's Law