5.5.2 Newton's Second Law

• What is Newton's Second Law?

  It explains how the motion of an object changes when a force is applied.
• What does Newton's Second Law quantitatively describe?

  The relationship between force, mass, and acceleration.
• What is the statement of Newton's Second Law?

  • The acceleration of an object is directly proportional to the resultant force acting on it.
  • It is inversely proportional to its mass.
• What is the mathematical 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 meters per second squared (m/s²).
• What are the definitions of force, mass, and acceleration in Newton's Second Law?

  • **Force (\( F \))**: The push or pull acting on an object causing it to accelerate.
  • **Mass (\( m \))**: The quantity of matter in the object; larger mass requires greater force for the same acceleration.
  • **Acceleration (\( a \))**: The rate at which the velocity of the object changes; greater force leads to greater acceleration.
• What is an example of Newton's Second Law in action with a car?

  • A car accelerates when the engine applies force.
  • More force or less mass results in greater acceleration.
• How does pushing an empty shopping cart differ from pushing a full one according to Newton's Second Law?

  • An empty cart accelerates more easily due to less mass.
  • A full cart requires more force to achieve the same acceleration because its mass is greater.
• What happens to two objects of different masses dropped from the same height in the absence of air resistance?

  • Both objects accelerate at the same rate due to gravity.
  • The force of gravity is proportional to their mass.
• What are the practical implications of Newton's Second Law in design and engineering?

  • Engineers use it to design vehicles, machines, and structures.
  • They calculate forces needed for desired accelerations to ensure safety and performance.
• How does Newton's Second Law apply to everyday activities?

  • Heavier objects require more force to accelerate.
  • Lighter objects accelerate more quickly under the same force.
• What are the units for force, mass, and acceleration?

  • **Force**: Newton (N) = kg·m/s²
  • **Mass**: Kilogram (kg)
  • **Acceleration**: Meters per second squared (m/s²)
• If a 10 kg box is pushed with a force of 50 N, what is its acceleration?

  5 m/s²
• What is the force required to accelerate a 15 kg object at 3 m/s²?

  45 N
• If a force of 60 N produces an acceleration of 4 m/s², what is the mass of the object?

  15 kg
• What are the key points of Newton's Second Law?

  • \( F = ma \): Describes the relationship between force, mass, and acceleration.
  • Force and acceleration are directly proportional.
  • Mass and acceleration are inversely proportional.
  • Crucial for analyzing motion and designing systems interacting with forces.