How Can Forces Affect Objects?

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# How Can Forces Affect Objects? - PowerPoint PPT Presentation

How Can Forces Affect Objects?. Stacking Robots. THINK ABOUT THIS?????? When the clowns are balanced, is their state of motion constant or changing? Did their speed or direction change?

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Presentation Transcript

### How Can Forces Affect Objects?

Stacking Robots

• When the clowns are balanced, is their state of motion constant or changing? Did their speed or direction change?

2. When the clowns are unbalanced, is their state of motion constant or changing? Did their speed or direction change?

What Happens to Wilson?

“Imagine that you are floating in outer space, far from any planet, star, or other mass.

The only thing that you have other than your space suit is your pet rock, Wilson. One

day, you and Wilson have an argument, and you angrily fling him away from you. How

will he travel? Will he ever slow down or come back? Will you ever know the comfort of

Explain Stacking Robots
• When the clowns are balanced, is their state of motion constant or changing? Did their speed or direction change?

Balanced Forces= Constant speed AND direction.

When the clowns are balanced, they are stationary or stay at rest. Speed is zero and there is no change in the direction of the clowns’ motion.

• When the clowns are unbalanced, is their state of motion constant or changing? Did their speed or direction change?

Unbalanced Forces= Changing speed OR direction

The clowns initially speed up in a downward direction, then for a brief moment in time they move at the same speed and direction before they slow down in an upward direction upon making contact with the floor, table or desk.

3. When the clowns were balanced, was their velocity constant or changing?

Balanced Forces= Constant velocity

4. When the clowns were unbalanced, was their velocity constant or changing?

Unbalanced Forces= Changing velocity

Misconceptions

True or False?

A force is necessary to keep object moving

Newton’s First Law of Motion states:

Objects in motion stay in motion in a straight line unless acted upon by an unbalanced force.

Outside forces such as friction, gravity, magnetic force, electrical, force, and air resistance slow/stop objects

True or False

If an object is at rest,

no forces are acting upon it

There are many forces acting on it

(gravity, air pressure, etc)

but they are all BALANCED

### Explain Balanced Forces

Explain Balanced Forces
• When all the forces acting on an object balance each other
• Balanced forces do not cause a change in motion
Normal Force

We call this NORMAL FORCE. The book is said to be at equilibrium since there are no unbalanced forces acting upon the book and it maintains its state of motion (it still sits on the table).

Lets say you are standing on the ground. Since the floor pushes upward on you and gravity is pulling down on you, you are at equilibrium.
Let’s say you give that book on the table a push…

The book goes temporarily into motion, but friction from the table and gravity doesn’t allow it to go far.

### Explain Unbalanced Forces

Explain Unbalanced Forces
• When all the forces acting on an object are not equal
• Unbalanced forces cause a change in motion

### Describe Friction

Describe Friction
• Force that resists motion between two touching surfaces
• Acts in the opposite direction of the object’s motion
• Produces heat
Explain Centripetal Force

Centripetal force is directed to the axis of rotation

Makes an object follow a curved path

Free-body diagrams

Free-body diagrams are used to show the relative magnitude and direction of all forces acting on an object.