ForceWork and Power
Formula for ForceForce = Mass * Acceleration
Force – push or pull•   a force always acts in a certain    direction• metric unit of force (N)ex. if you push something, ...
Mass   How much matter is in an objectMeasured in grams (g) or Kilograms (kg)
Acceleration          Change in SpeedMeasured in meters per second squared               (m/s2)
Force examplesWeight is a forceWhy is weight a force?Name 3 other forces in your life.
Forces in Nature•   Electric force    – ex. lightning•   Magnetic force    – ex. magnetic poles•   Gravity
What is gravity?•   The force that attracts a body toward the    center of the earth, or toward any other    physical body...
Gravity•   the greater the distance between two    objects, the smaller the gravitational    force    – the force of gravi...
What is air resistance?•    air resistance    – force that opposes the movement of an      object in air
Air Resistance•   a larger surface area usually results in    greater air resistance•   lighter objects feel more air resi...
Terminal Velocity•    speed at which air resistance and     gravity acting on an object are equal    – as an object falls,...
Vacuum – empty space•    in a vacuum, all objects fall at the     same speed
What is friction?•   Friction    – force that opposes the motion of an      object      •    the force of friction works i...
Types of Friction•   Sliding Friction    – the source of friction is the contact      between two surfaces, at least one o...
Types of Friction•   Air Resistance    – friction results from air pushing on an      object as it is moving
Types of Friction•   Rolling Friction    – friction between two surfaces that are not      in constant contact      •   ex...
Friction•   friction makes motion possible•   friction also makes it hard to move    objects•   reducing friction makes it...
How can friction be reduced?  •   by changing sliding friction into rolling      friction  •   by using lubricants      – ...
What is pressure?•   Pressure    – force per unit area
Pressure•   pressure is the amount of force acting    on a surface•   pressure equals force divided by area    – p = f/a
Pressure•   pressure can be changed by changing    the amount of force acting on an area•   pressure can be changed by cha...
Fluid Pressure•   pressure in gases and liquids
Air Pressure•   air pressure is caused by the motion    of particles in the air•   you do not feel the weight of the air  ...
Air Pressure•   air pressure changes with altitude    – the higher you are, the lower the air      pressure
Air Pressure•   Barometer    – instrument used to measure air pressure
Water Pressure•   the force of water pressure on an    object is the same in all directions•   water pressure changes with...
Water Pressure•   Manometer    – instrument used to measure pressure in a      liquid
What is Bernoulli’s principle?  •   Bernoulli’s Principle      – principle that states that as the speed of a        fluid...
Bernoulli’s Principle•   airplane wings are designed to use    Bernoulli’s principle    – air traveling over the wings mov...
Bernoulli’s Principle•   three forces combine to help an    airplane fly    – the upward force on a plane’s wing is      c...
Work is the transfer of energy through motion. Inorder for work to take place, a force must be exertedthrough a distance. ...
Formula for WorkWork can be calculated by using the  following formula:         Work=force x distance            J   =   N...
Work is done on thebooks when they arebeing lifted, but nowork is done onthem when they arebeing held orcarried horizontal...
PowerRate at which work is performed orenergy is expended
W                            P=                               tPower equals Work divided by Time  W     =     J       /   ...
Types of PowerElectrical Power   Uses electrical energy to do workMechanical Power   Uses mechanical energy to do work   (...
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Force work power

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  • Energy, Work, and Power Principles of Engineering TM Unit 1 – Lesson 1.2 – Work, Energy, and Power
  • Force work power

    1. 1. ForceWork and Power
    2. 2. Formula for ForceForce = Mass * Acceleration
    3. 3. Force – push or pull• a force always acts in a certain direction• metric unit of force (N)ex. if you push something, the force is in the direction of the push
    4. 4. Mass How much matter is in an objectMeasured in grams (g) or Kilograms (kg)
    5. 5. Acceleration Change in SpeedMeasured in meters per second squared (m/s2)
    6. 6. Force examplesWeight is a forceWhy is weight a force?Name 3 other forces in your life.
    7. 7. Forces in Nature• Electric force – ex. lightning• Magnetic force – ex. magnetic poles• Gravity
    8. 8. What is gravity?• The force that attracts a body toward the center of the earth, or toward any other physical body having mass• Sir Isaac Newton – 1642 – 1727 – The Principia
    9. 9. Gravity• the greater the distance between two objects, the smaller the gravitational force – the force of gravity decreases by the amount equal to one divided by the distance (d) squared • 1/d2
    10. 10. What is air resistance?• air resistance – force that opposes the movement of an object in air
    11. 11. Air Resistance• a larger surface area usually results in greater air resistance• lighter objects feel more air resistance than heavier objects
    12. 12. Terminal Velocity• speed at which air resistance and gravity acting on an object are equal – as an object falls, it’s speed increases at a steady rate until it reaches it’s terminal velocity
    13. 13. Vacuum – empty space• in a vacuum, all objects fall at the same speed
    14. 14. What is friction?• Friction – force that opposes the motion of an object • the force of friction works in the opposite direction of the force of motion
    15. 15. Types of Friction• Sliding Friction – the source of friction is the contact between two surfaces, at least one of which is in motion
    16. 16. Types of Friction• Air Resistance – friction results from air pushing on an object as it is moving
    17. 17. Types of Friction• Rolling Friction – friction between two surfaces that are not in constant contact • ex. wheels
    18. 18. Friction• friction makes motion possible• friction also makes it hard to move objects• reducing friction makes it easier to move objects
    19. 19. How can friction be reduced? • by changing sliding friction into rolling friction • by using lubricants – Lubricants – substances that reduce friction
    20. 20. What is pressure?• Pressure – force per unit area
    21. 21. Pressure• pressure is the amount of force acting on a surface• pressure equals force divided by area – p = f/a
    22. 22. Pressure• pressure can be changed by changing the amount of force acting on an area• pressure can be changed by changing the area on which a force acts
    23. 23. Fluid Pressure• pressure in gases and liquids
    24. 24. Air Pressure• air pressure is caused by the motion of particles in the air• you do not feel the weight of the air because the pressure inside your body is equal to the air pressure
    25. 25. Air Pressure• air pressure changes with altitude – the higher you are, the lower the air pressure
    26. 26. Air Pressure• Barometer – instrument used to measure air pressure
    27. 27. Water Pressure• the force of water pressure on an object is the same in all directions• water pressure changes with depth – the deeper you are, the greater the water pressure
    28. 28. Water Pressure• Manometer – instrument used to measure pressure in a liquid
    29. 29. What is Bernoulli’s principle? • Bernoulli’s Principle – principle that states that as the speed of a fluid increases, its pressure decreases
    30. 30. Bernoulli’s Principle• airplane wings are designed to use Bernoulli’s principle – air traveling over the wings moves faster than air underneath – this reduces the pressure on top of the wing, allowing it to be pushed upward
    31. 31. Bernoulli’s Principle• three forces combine to help an airplane fly – the upward force on a plane’s wing is called lift – a forward force, or thrust, helps the plane take off and maintain air speed – the air resistance on a plane is called drag
    32. 32. Work is the transfer of energy through motion. Inorder for work to take place, a force must be exertedthrough a distance. The amount of work donedepends on two things: the amount of force exertedand the distance over which the force is applied.There are two factors to keep in mind whendeciding when work is being done: something has tomove and the motion must be in the direction of theapplied force.
    33. 33. Formula for WorkWork can be calculated by using the following formula: Work=force x distance J = N X m
    34. 34. Work is done on thebooks when they arebeing lifted, but nowork is done onthem when they arebeing held orcarried horizontally.
    35. 35. PowerRate at which work is performed orenergy is expended
    36. 36. W P= tPower equals Work divided by Time W = J / s Watt is the base unit of Power One watt is equal to 1 joule of work per second
    37. 37. Types of PowerElectrical Power Uses electrical energy to do workMechanical Power Uses mechanical energy to do work (linear, rotary)Fluid Power Uses energy transferred by liquids (hydraulic) and gases (pneumatic)

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