Forces in Motion

1
Forces in Motion

• What is a force?
• A force is a Push or a Pull that one body exerts
  on another.
• List some examples of forces.
• Kicking a soccer ball
• Opening a jar of peanut butter
• Pulling a cart

2
The 4 Classic Forces

• Electromagnetic (or magnetic)
• Gravitational
• Strong (wait for quantum physics!)
• Weak (wait for quantum physics!)

3
What happens to an object when you exert a force
on it?

• A force can change the motion of an object.
• Example hitting a tennis ball changes the
  direction of the tennis ball by applying a force

4
Types of Forces

• Net Force sum of all the forces acting on an
  object.
• Net forces of zero do not change the speed or
  direction of an object.
• Net forces greater than zero either change the
  speed or direction of an object.

5
Types of Forces

• Balanced Forces - equal in size and opposite in
  direction. They basically cancel each other out!
• Unbalanced Forces - unequal forces cause the
  object to move in the direction of the larger
  force.

6
Balanced or Unbalanced Net Force?

• Extremely unbalanced!
• Rider has lost all friction but his inertia is
  still very great. OUCH!!!

7
Balanced or Unbalanced Net Force?

• Extremely unbalanced!
• Rider has lost all friction but his inertia is
  still very great. OUCH!!!

8
Try it, Youll Like It!

• Working in Pairs, complete Introducing Newtons
  First Law Lab.
• Be in your seat for the last 5 minutes of class
  and work on Targets 1-3 and Vocabulary words 1-3.

9
Inertia Mass

• Why is it harder to move a bowling ball than a
  golf ball?
• A bowling ball has more MASS than a golf ball
  so it also has more INERTIA!

10
Inertia

• Inertia is an objects resistanceto a change in
  motion (or force).

11
Newtons 1st Law Inertia!

• An object at rest will stay at rest unless an
  unbalanced net force acts on it.
• An object in motion will stay in motion (same
  speed, same direction) unless an unbalanced net
  force acts on it.
• Translation Things want to keep doing what
  theyre already doing!

12
Car Crash Inertia!

• Inertia - your body keeps moving until its
  stopped by some other force
• What is the correlation between seatbelts and
  Inertia?
• Why would you want backseat riders to wear a
  seatbelt?
• What can happen to any loose items in a car
  during an impact?

13
Now You Discuss It!

• Discuss vehicle safety features with your
  partner.
• Figure out how the safety features pertains to
  Inertia.