Science Q4

• Momentum


  Mass in motion
• According to Newton's first law of motion, a body will keep its state of motion - moving at constant velocity or being at rest - unless an unbalanced force act on its
• Inertia


  • Keeps bodies moving on
  • Force or speed of movement is called MOMENTUM
• Law of Inertia


  An object at rest remains at rest and an object in motion remains in motion until it is acted upon by an unbalanced force
• Law of Acceleration


  The acceleration of an object depends on the mass of the object and the amount of force applied
• Law of Interaction


  For every action, there is an equal and opposite reaction
• Momentum


  • The object has mass
  • The object is moving
• Momentum

  The product of mass and velocity of a body
• 3 Ways a body can have high-moving inertia or momentum

  • A body with little mass and high velocity
  • A body with large mass moving at slow but steady pace
  • A large mass moving fast
• The greater the mass and/or velocity of a body, the greater the magnitude of its momentum
• The greater the momentum of a moving body, the more difficult it is to stop at a given time
• The momentum of a body is always in the same direction as its velocity; thus, momentum is a vector quantity
• Sample Problem Solving 1

  1. Calculate the momentum of a 1,360-kg car with a velocity of 18-m/s

  2. p = 1360kg x 18m/s

  3. p = 24,480kgm/s
• Sample Problem Solving 2

  1. Calculate the mass of a school bus with momentum of 152,625 kg.m/s and velocity of 11.1 m/s

  2. m = 152,625 kg.m/s / 11.1 m/s

  3. m = 13,750 kg
• Sample Problem Solving 3

  1. Calculate the velocity of a 1,450.80-kg automobile with momentum of 60,500.10 kg.m/s

  2. v = 60,500.10 kg.m/s / 1,450.8kg

  3. v = 41.70m/s
• Impulse


  The product of the average force and the time interval during which the force acts
• Impulse is a term that quantifies the overall effect of a force acting over time
• Impulse


  1. Derived from the equation F = ma, which comes from Newton's second law of motion

  2. Impulse is another quantity used in analyzing collisions

  3. Impulse is a vector quantity

  4. Impulse (I) quantifies the continuous application of a force (F) over a time interval (t). In symbols, I = Ft
• Impulse


  • Depends on the force acting on the object
  • Depends on the time that the force acts
  • Impulse is directly proportional to Force and Time
• I = Ft shows why the SI unit for impulse is the Newton · second. There is no special name for this unit, but it is equivalent to a kg · m /s. 1N.s = 1 (kg.m/s²) (s) = 1kg.m/s.
• Sample Problem Solving 1

  1. Calculate the impulse of a bullet with force of 40N and time of 0.35s

  2. I = 40N x 0.35s

  3. I = 14N•s
• Sample Problem Solving 2


  1. Calculate the force of a rocket engine designed to deliver an impulse of 6.0 kg.m/s over 0.75s

  2. F = 6N.s / 0.75s

  3. F = 8N
• If momentum changes, it's because mass or velocity change. Most often mass doesn't change so velocity changes and this is acceleration.
• Sample Problem Solving 3

  1. Calculate the force of a 12 kg model rocket engine with velocity of 7.2 m/s and burn time of 0.50 s

  2. I = m Δv

  F = m Δv/t

  F = (12kg x 7.2m/s) / 0.5s

  F = 172.8N
• Sample Problem Solving 4

  Calculate the impulse imparted to a 1.5 kg ball with initial velocity of 23 m/s and final velocity of 18 m/s

  Impulse = m₁v₁ - m₂v₂

  Impulse = 1.5kg(23m/s - (-18m/s))

  Impulse = 61.5 N·s