Forces and the laws of motion
Sponsored Links
This presentation is the property of its rightful owner.
1 / 20

Forces and the Laws of Motion PowerPoint PPT Presentation

  • Uploaded on
  • Presentation posted in: General

Forces and the Laws of Motion. Forces. Force is a push or pull on an object. Unit for force: N or Newton. Balanced forces Where there are two forces that counteract each other and result in no movement (EQUAL) Unbalanced forces One force is greater than the other force. (UNEQUAL).

Download Presentation

Forces and the Laws of Motion

An Image/Link below is provided (as is) to download presentation

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

Forces and the Laws of Motion


  • Force is a push or pull on an object.

  • Unit for force:

    N or Newton.

  • Balanced forces Where there are two forces that counteract each other and result in no movement (EQUAL)

  • Unbalanced forces

    One force is greater than the other force.



  • A force that resists motion and can cause heat

  • Lubricants help reduce friction

  • Types of friction

    • Sliding

    • Rolling

    • Fluid

    • Static

  • Types of friction

  • Static

  • acts on objects that are not moving

  • Always acts in opposite direction to applied force

  • Sliding

  • Opposes direction of motion as an object slides

  • Less then static friction

  • Rolling

  • Friction that acts on rolling objects

  • 100 to 1000 times less than static and sliding friction

  • Fluid

  • Opposes the motion of an object through a fluid

  • Fluids include gases and liquids

  • Air resistance – fluid friction acting on an object moving

  • through the air

Newton’s Laws of Motion

  • 1st Law: Objects at rest remain at rest, or objects in motion remain in motion unless acted upon by a force. (unbalanced)

  • 2nd Law: The acceleration of a body depends on the ratio of the acting force to the mass of the body. (unbalanced)

    • F = m x a

  • 3rd Law: for every action there is an equal and opposite reaction. (balanced)

  • 1st Law of Motion (Law of Inertia)

    • Inertia: force that is resistant to the direction of the motion

      • The forces are Unbalanced

    • Examples: Inertia belts (seat belts)

    2nd Law of Motion

    • Concept: Acceleration

      • The forces are unbalanced

    • Examples: hitting a golf ball gently vs. hard.

    • F = ma

    Answer = _50__ newtons

    Problem 1

    How much force is needed to accelerate a

    500.0 kg car at a rate of 4 000 m/s/s?

    Problem 2

    A 100 N force causes an object to accelerate at

    2 m/s/s. What is the mass of the object?

    Problem 3

    A 1.5 kg ball is kicked with a force of 450 N.

    What acceleration did the ball receive?

    3rd Law of MotionAction/ Reaction

    • Concept: Action/Reaction of objects

      • Forces are balanced

    • Examples: Stationary objects, rockets being launched

    Laws of motion Interactives



    Motion of a falling object after being

    given an initial forward velocity

    Combination of initial vertical force

    and downward force of gravity

    Causes object to follow a curved path

    Gravity and Free Falling Objects

    • Gravity: The attraction between two objects.

    • All objects fall at a rate of 9.8 m/s2

    • Gravity acts betweentwo masses

    • All masses exert the force of gravity – universal force

    • Galileo did an experiment at the leaning tower of Pisa in Italy with bowling balls. Both balls fell at the same rate.

    Air Resistance

    • Force that slows down falling objects due to the atmosphere and surface area of the object.

    Newton’s Law of Universal Gravitation

    • Shows that objects are attracted to one another in proportion to their masses and their distances away from the object.

    Feather vs. Rock

    • Earth: feather would float down (air resistance) while the rock would drop at 9.8 m/s/s

    • Moon: feather and rock would drop at same rate due to no atmosphere and air resistance.

    What about a vacuum?

    • vac·u·um[ vákyooəm ]

    • space empty of matter: a space completely empty of matter but not achievable in practice on Earth

    • space with all gas removed: a space from which all air or gas has been extracted

    • emptiness caused by absence: an emptiness caused by somebody or something's absence or removal

    • Both fall at the same rate due to there being no air.

    Gravity and Weight



    Mass – measure of amount of inertia

    Weight – force of gravity pulling on an object

    Weight is product of mass and acceleration due to gravity ( 9.8 m/s/s)

    W = mg

    W- weight in newtons

    m- mass in kilograms

    g- acceleration due to gravity in meters per second squared

  • Login