Coverage of the 1st Long test

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Coverage of the 1st Long test

• Newtons Laws of Motion
• graphing vectors
• calculating components of vectors
• (horizontal and vertical components)
• getting the resultant vector using the component
  method
• free- body diagram
• Static equilibrium
• calculating forces involved in a given system

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Static Equilibrium

• Condition 1
• S Fx 0
• S Fy 0
• S Fz 0
• Condition 2
• The sum of the
• torque, ?, is zero.

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Center of Gravity

• the point where the force of gravity is
  concentrated
• When the center of
• gravity falls within the
• base of the object, then
• the object is stable.

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Static
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Object in free-fall
Fgravity
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Objects falling at constant velocity (terminal
velocity)

• F air friction
• F gravity

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Object sliding at constant velocity(the surface
is frictionless)

• F normal
• F gravity

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Object sliding without friction
F normal
F gravity
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Is the box accelerating?

• mass of the block 10kg
• 10N 5N
• F applied Ff

• F normal
• 10 N
• 5N
• F gravity

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Is the box accelerating?

• mass of the block 10kg
• S Fy Fnormal Fgravity 0
• Fgravity Weight
• mass X acceleration
• 10 kg X - 9.8 m/s2
• - 98 kgm/s2
• - 98 N
• S Fy Fnormal ( -98 N) 0
• Fnormal 98 N

• F normal
• F applied 10 N
• Ff 5N

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Is the box accelerating?

• mass of the block 10kg
• S F x Fapplied Ff
• S Fx 10 N (-5N) 5N
• Fnet 5N massX acceleration
• 5N 10 kg X a
• a 0.5 m/s2

• F normal
• F applied 10 N
• Ff 5N

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Note There is friction between the load and the
incline.

• http//www.google.com.ph/imgres

Draw the FBD of the box
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A
B
C
Draw the FBD of the knot (include the angle).
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Summary

• The object is in static equilibrium if it is not
  moving and not rotating.
• A free-body diagram can be drawn to evaluate the
  effect of forces on the object.
• There is always a force of gravity (also known as
  weight) which is equal to the product of the mass
  and acceleration due to gravity.
• There is a normal force perpendicular to the
  surface that supports and balances the object
  vertically.