Mr. Perez

1
Mr. Perez

• Grade 6 Science
• Newtons 1st Law of Motion and Inertia (S.C. Part
  I)

2
Newtons First Law of Motion

• Newtons first law of motion explains how inertia
  affects moving and nonmoving objects
• Newtons first law states that an object will
  remain at rest or move at a constant speed in a
  straight line unless it is acted on by an
  unbalanced force
• Inertia causes baseball players to run in
  straight lines and round the bases instead of
  making sharp turns

a acceleration v velocity
3
Part 1

• What is Newtons 1st Law of Motion?
• An object at rest wants to stay at rest. An
  object in motion wants to stay in motion.
• What is inertia?
• Inertia is the tendency of an object to keep
  doing whatever its already doing.
• If the object is resting, it stays resting. If
  its moving, it stays moving.

4
Part 1

• What is an example of inertia?
• If a person is sitting in a moving car, and the
  car stops, the person keeps moving forward.
• Why? Inertia keeps moving the person forward
• How does inertia explain why you should wear a
  seatbelt in a moving car?
• When a car stops suddenly, inertia keeps
  passengers moving forward. The seat belt stops
  them from smashing into the dashboard (and
  avoiding injuries). The force needed to slow a
  person from 50km/h to zero in 0.1 seconds is
  equal to 14 times the force of gravity exerted on
  a person.

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What happens in a crash?

• The law of inertia can explain what happens in a
  car crash.
• When a car traveling at 50 km/h collides head on
  with something solid, the car crumples, slows
  down, and stops in 0.1 sec.

6
Part 1

• Does the BAAD that Doug is holding have inertia?
• Yes, the BAAD has inertia. An object has inertia
  whether it is moving OR standing still.
• How does inertia explain why the BAAD hits
  Cramwood in the back of the head?
• The BAAD is moving along with the bike. When
  Cramwood stops, inertia causes the BAAD to keep
  moving forward. The forward motion of the BAAD
  smacks Cramwood in the back of the head after the
  bicycle stops moving forward.