Force

1 / 14

# Force - PowerPoint PPT Presentation

Force. Definition: A push or a pull Force can cause motion SI unit -&gt; Newton (N)= 1 kg x 1 m/s 2 Sometimes pound ( lb ) can be used as a unit for force 1 Newton=0.22481 pounds force. Combining Forces. Balanced Force Equal and opposite forces = ‘balanced’

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'Force' - duane

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Force

Definition:

• A push or a pull
• Force can cause motion
• SI unit -> Newton (N)= 1 kg x 1 m/s2
• Sometimes pound (lb) can be used as a unit for force
• 1 Newton=0.22481 pounds force
Combining Forces
• Balanced Force
• Equal and opposite forces = ‘balanced’
• Balanced forces give no motion

No motion of hands

Combining Forces
• Unbalanced force – more force in one direction (net force)
Net Force
• Bigger force to the right
• Smaller force to the left
• Net force to the right
III. Friction and Gravity
• Friction – a force that opposes motion
• Caused by the interaction between two touching surfaces rubbing against each other
• Four Types
a. Static
• Friction that acts on something that is not moving
• No heat or wear is generated
b. Sliding
• Force resulting when pushing or pulling an object over a surface.
c. Rolling
• Contact is reduced because of rollers or wheels or ball bearings.
d. Fluid friction
• Resistance from a “fluid”
• Fluids are liquids and gases.
Reducing friction
• A smooth surface does not demonstrate as much friction as a rough surface.
• Waxing, oiling, etc. can be used to reduce friction.
Coefficient of Friction
• µ= “coefficient of friction”  represents the roughness of the surfaces in contact.
• In reality there two main subtypes:
• µs- Static friction to get it moving
• µk- Kinetic friction to keep it moving
• µs> µk needed for movement to occur
Gravity

– force of attraction between two objects

---> pulling force

Factors Affecting Gravity

• Mass – more mass, more gravity
• Distance – closer, more gravity

http://www.exploratorium.edu/ronh/weight/

End Check- Complete on separate sheet of paper
• 1. Describe three ways in which a car’s velocity will change
• 2. Identify a one situation involving unbalanced force and one situation involving balanced force. Explain how it each affect the motion of an object.
• 3. Arrange the following pairs of surfaces in order of most friction to least friction
• A shoe sole and a waxed basketball court
• A shoe sole and the frozen surface of a lake
• A shoe sole and the sidewalk
End Check- Complete on separate sheet of paper
• 4. Explain why Venus, which is slightly less massive than Earth, experiences a stronger gravitational pull from the sun than Earth does.
• 5. What is the average acceleration of a scooter that starts at rest and moves straight ahead at 12 m/s in 24 s.
• 6. Which will be moving faster after 3.0 s, a cyclist maintaining a constant velocity of 15 m/s straight ahead or a race car accelerating forward from a stoplight at 4.0 m/s2?