Physics Force and Motion

• What must act on an object for its velocity to change?

  A resultant force
• In which direction does acceleration act in relation to the resultant force?

  In the same direction
• What causes the force of gravity near the Earth?

  The planet's gravitational field strength
• What is weight defined as?

  The force acting on an object due to gravity
• How can weight be measured?

  • Using a calibrated spring balance
  • Using a newtonmeter
• What is the formula for calculating weight?

  Weight = mass × gravitational field strength
• What does the equation W = mg represent?

  Weight equals mass times gravitational strength
• How are weight and mass related?

  They are directly proportional
• What happens to an object's weight if its mass doubles?

  Its weight also doubles
• What does Newton's Second Law state about acceleration?

  • Acceleration is proportional to resultant force
  • Acceleration is inversely proportional to mass
• What is the equation linking resultant force, mass, and acceleration?

  Resultant force = mass × acceleration
• What does the equation F = ma represent?

  Resultant force equals mass times acceleration
• What does inertial mass measure?

  Difficulty in changing an object's velocity
• How can inertial mass be calculated?

  Inertial mass = resultant force / acceleration
• What are the two forces acting on an object falling through a fluid?

  Weight and drag force
• What happens to the drag force as an object falls faster?

  It increases
• What occurs to the resultant force as drag force increases?

  It gets smaller
• What happens to the acceleration of a falling object as it falls?

  It decreases
• What is terminal velocity?

  Constant velocity when drag equals weight
• What is the acceleration due to gravity?

  9.8 m/s²
• What is momentum?

  A property of all moving objects
• What type of quantity is momentum?

  A vector quantity
• What does momentum depend on?

  Mass and velocity of an object
• What is the equation for momentum?

  Momentum = mass × velocity
• What does the Law of Conservation of Momentum state?

  Total momentum before equals total after
• How can the Law of Conservation of Momentum be expressed for colliding objects?

  m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
• What does m₁ represent in the conservation of momentum equation?

  Mass of object 1
• What does u₁ represent in the conservation of momentum equation?

  Initial velocity of object 1
• What does v₁ represent in the conservation of momentum equation?

  Final velocity of object 1
• What happens to a skydiver's weight when they leave the plane?

  It is greater than air resistance
• What occurs when air resistance and weight are equivalent?

  Terminal velocity is reached
• What happens when a skydiver opens their parachute?

  Air resistance becomes greater than weight
• What is the resultant force when a skydiver reaches the ground?

  It is zero
• What does terminal velocity allow a skydiver to do safely?

  Land without injury
• What is the equation for calculating the spring constant?

  • Spring constant = force / extension
  • Can also apply for compression
• What is deceleration?

  Negative acceleration
• What is deformation in the context of forces?

  Change in shape due to applied force
• What do graphs of force against extension show for elastic objects?

  • Relationship between force and extension
  • Indicates elastic limit