Skydiving Video

http://www.youtube.com/watch?v=ur40O6nQHsw&feature=related&noredirect=1

On the back of your notes (2nd Page):

Write down some examples of situations you think understanding forces would be important other than skydiving?

Purple Student Learning Map

• LEFT SIDE

• Concept: Basic Forces

• LEQ3: How do multiple forces interact when applied to the same object?

Vocabulary

10) Balanced Forces11) Unbalanced Forces12) Net Force

Net Force

Force Diagram

• A force diagram is a picture that shows how a force is acting on an object.

• Force diagrams shows each force as an arrow pushing or pulling on the object and a number showing the magnitude (aka size).

Object

5 N

Force Diagram Practice

Using the diagram below, find each piece of information.

A)Push or pull?

B)Direction the object is moving

C)The amount of force being applied to the object with units

D)The object3 N

Push

To the left

3 Newtons

A cow!

Net Force

• If more than one force acts on an object, it is possible to calculate the total or net force on the object.

• These forces can either work together or against each other.

Additive Net Force

• If the forces are going in the same direction, then they work together.

• The net force is the sum of the individual forces.

5 N3 N

8 N

Individual Forces Net Force

Subtractive Net Forces

• If the forces are going in opposite directions, then the forces are working against each other.

• The net force is the difference between the individual forces.

5 N 3 N 2 N

Individual Forces Net Force

Unbalanced Net Force

• When the net force on an object is not zero, then the forces acting on that object are unbalanced.

• Unbalanced forces change the motion (speed or direction) of an object.

4 N 7 N 3 N

Balanced Net Forces

• When the net force on an object is zero, then the forces acting on that object are balanced.

• Balanced forces do not affect the motion of the an object.

• Balanced forces must be equal in magnitude but opposite in direction.

4 N 4 N 0 N

Amazing Forces!!!!

• Balanced or Unbalanced?

Practice 1

You push on a book with a force of 10 N and Chris pushes on the book but against you with a force of 10 N.

• Draw a force diagram.• Determine the net force.• Decide if the forces are

balanced.10 N 10 N Net Force:10 N – 10 N = 0 N

Balanced!

Practice 2

The blue team pulls on the rope with a force of 55 N while the red team pulls against them with a force of 45 N.

• Draw a force diagram.• Determine the net force.• Decide if the forces are

balanced.55 N 45 N Net Force:55 N – 45 N = 10 N

Unbalanced!

Practice 3

A man pushes down on a button with a force of 2 N while gravity pulls on it with a force of 6 N.

• Draw a force diagram.

• Determine the net force.

• Decide if the forces are balanced.

6 N

2 N

Net Force:2 N + 6 N = 8 N

Unbalanced!

Practice 4

Label each image as an example of a balanced or unbalanced force:

Balanced

Unbalanced

Unbalanced