Newton's Second Law

• What does Newton's second law describe?

  Change in motion from a resultant force

  
• What does Newton's Second Law state about resultant force and acceleration?

  Resultant force is proportional to acceleration
• What is the formula for Newton's Second Law?

  F = ma

  
• What does F represent in the formula F = ma?

  Resultant force, measured in newtons (N)
• What does m represent in the formula F = ma?

  Mass of the object, measured in kilograms (kg)
• What does a represent in the formula F = ma?

  Acceleration, measured in metres per second squared (m/s²)
• In which direction does acceleration act according to Newton's Second Law?

  Same direction as the resultant force
• What happens when unbalanced forces act on an object?

  The object experiences a resultant force
• What occurs if the resultant force acts along the direction of motion?

  The object will speed up (accelerate)
• What occurs if the resultant force acts against the direction of motion?

  The object will slow down (decelerate)
• What happens if the resultant force acts at an angle to the direction of motion?

  The object will change direction
• What type of quantity is force?

  Vector quantity with magnitude and direction
• How is the resultant force defined?

  Vector sum of all forces acting on a body
• What determines the positive direction for a moving object?

  The direction of motion is positive
• How can the magnitude and direction of resultant force be found?

  By combining vectors or using scale drawings
• What type of quantity is acceleration?

  Vector quantity with magnitude and direction
• What happens to acceleration if the resultant force acts in the direction of motion?

  Acceleration is positive
• What happens to acceleration if the resultant force opposes the direction of motion?

  Acceleration is negative
• What is the effect of a resultant force opposing motion?

  Causes deceleration, not backward motion
• How does mass affect the acceleration of a falling object?

  Acceleration is independent of mass without drag
• What experiment demonstrated that mass does not affect falling acceleration?

  Astronauts dropped a hammer and feather
• What is the condition for the hammer and feather to hit the ground simultaneously?

  No air resistance on the Moon
• What is the force due to air resistance acting on the rocket?

  500 kN

  
• How do you determine the resultant force on the rocket?

  By calculating F = 15 MN - 8 MN - 500 kN
• What is the equation for Newton's second law rearranged for acceleration?

  a = F/m
• How do you calculate the acceleration of the rocket?

  By using a = F/m with F = 6.5 MN
• How is Newton's second law related to momentum?

  Resultant force equals rate of change of momentum
• What is the formula for momentum?

  p = mv
• What is the rate of change of momentum formula?

  ∆p/∆t = m∆v/∆t
• How is force defined in terms of momentum?

  F = m∆v/∆t
• How is acceleration defined in terms of momentum?

  a = ∆v/∆t
• What is the general rule for positive and negative directions in motion?

  Forward, upwards, right are positive
• What should be consistent throughout calculations regarding direction?

  Choose one direction as positive or negative