3. Dynamics

• What does Newton's 1st law state about an object's motion?

  An object will remain at rest or traveling at a constant velocity until it experiences a resultant force.
• How does Newton's 2nd law relate force, mass, and acceleration?

  The acceleration of an object is proportional to the resultant force experienced by the object, expressed as $F =$$ma$.
• In which direction do the resultant force and acceleration act according to Newton's 2nd law?

  The resultant force and acceleration are always in the same direction.
• What does Newton's 3rd law state about forces?


  For each force experienced by an object, the object exerts an equal and opposite force.
• How does mass affect acceleration for a given resultant force?

  The larger the mass of an object, the smaller the acceleration it experiences for a given resultant force.
• If object 1 has a mass of 1 kg and object 2 has a mass of 10 kg, both experiencing a resultant force of 10 N, what is their acceleration?


  Object 1 has an acceleration of $10 \text{ ms}^{-2}$ and object 2 has an acceleration of $1 \text{ ms}^{-2}$.
• What is linear momentum?


  Linear momentum is the product of mass and velocity of an object.
• How is force related to momentum according to Newton's 2nd law?


  Force is the rate of change of momentum.
• How can the weight of an object be calculated?


  The weight of a body can be calculated by finding the product of its mass and $g$ (the acceleration due to gravity).
• What happens to the weight of a body in a uniform gravitational field?


  A body falling in a uniform gravitational field will experience a constant weight.
• What are the steps of an object's motion in a uniform gravitational field starting from rest?


  1. The object experiences weight downwards and air resistance upwards.
  2. As the object's velocity increases, air resistance increases, decreasing resultant force and acceleration.
  3. When weight equals air resistance, the object travels at terminal velocity.
• How does air resistance affect projectile motion?


  Air resistance affects both vertical and horizontal components, reducing maximum height and distance traveled.
• What does the principle of conservation of momentum state?


  Momentum is always conserved in any interaction where no external forces act.
• In a collision, how is momentum before the event related to momentum after the event?


  The momentum before an event is equal to the momentum after the event.
• How do you calculate the velocity of two vehicles after a collision?


  Use the total momentum before the collision to find the velocity after the collision.
• What is the formula for calculating weight?

  Weight is calculated as $W =$$mg$.
• What are the types of collisions and their characteristics?


  • Elastic: Both momentum and kinetic energy are conserved.
  • Inelastic: Only momentum is conserved; kinetic energy is converted into other forms.
• What is a perfectly elastic collision?


  In a perfectly elastic collision, the relative speed of approach before the collision equals the relative speed of separation after the collision.
• In a collision between two steel balls of equal mass, what happens to their velocities?


  The ball at rest moves away at a velocity equal to the relative speed of approach of the moving ball.
• What happens to kinetic energy in most collisions?


  In most collisions, kinetic energy is not conserved and is converted into other forms of energy.
• How is kinetic energy transformed during a vehicle collision?

  Kinetic energy is converted into elastic potential energy, thermal energy, and sound energy through deformation.