Forces

• What is a scalar quantity?

  A scalar quantity is a physical quantity that has magnitude but no direction.
• What is a vector quantity?

  A quantity that has both magnitude and direction.
• Give 3 examples of a scalar quantity?

  Time, temperature, mass
• Give 3 examples of a vector quantity?

  Force, velocity, acceleration
• Define Distance

  The length a space between 2 places
• Define displacement

  The shortest distance between 2 places with a direction
• What is the equation for speed?

  Speed = Distance / Time
• What is the equation for Acceleration?

  Change in velocity/Time
• What is the acceleration on a velocity time graph?

  The gradient
• Describe the differences between distance and displacement

  Distance has magnitude where as displacement has magnitude and direction
• Give 3 contact forces?

  Friction, tension, normal force
• Give 3 non-contact force?

  Gravity, magnetic force, electrostatic force
• What is the equation for elastic potential energy?

  The equation for elastic potential energy is E = 1/2 kx^2, where E is the elastic potential energy, k is the spring constant, and x is the displacement from the equilibrium position.
• What is elastic potential energy measured in?

  Joules
• What is resultant force?

  The overall force acting on an object.
• What is Newton's First Law also known as?

  Inertia
• What is terminal velocity?

  Constant speed in a constant direction.
• What is stopping distance?

  Thinking distance + Braking Distance.
• State Newton's first law of motion

  • Stationary object with a resultant force of 0 will remain stationary
  • Moving object with a resultant force of 0 will have a constant velocity
• What can thinking distance be affected by?

  Alcohol, fatigue and drugs
• What is the general human reaction time?

  0.2 - 0.9
• What can braking distance be affected by?

  Speed, road conditions, tire quality, and vehicle weight.
• What is momentum?

  The product of an object's mass and velocity.
• What is the conservation of momentum?

  The principle that the total momentum of a closed system remains constant if no external forces act on it.
• What is momentum measured in?

  Kilogram meters per second (kg m/s)
• what is the equation of momentum?

  \(p = mv\)
• How do planets show inertia?

  Planets do not show inertia due to their weight - this means that the suns gravitational field pulls the planet into orbit. Therefore, the planets do not have inertia as they don't have constant velocity.
• What is Newtons second law?

  Force equals mass times acceleration.
• What is Newton's third law

  Each action has an equal and opposite reaction
• What is the method to prove Newtons Second Law?

  • position on a track on a bench w/ a bench pulley at one end w/ two light gates above track
  • connect trolley to hanging mass by string, length of track, passing over pulley
  • set data logging software & calculate acceleration
  • 5x100g mass on trolley
  • 100g mass added to string
  • Release trolley, record acceleration
  • Repeat twice & calculate average acceleration
  • Move 100g from trolley to string
  • Repeat steps 6-8 until no masses left on trolley