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Coverage of the 1st Long test. Newton’s 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. 37°.
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Coverage of the 1st Long test • Newton’s 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
Static Equilibrium Condition 1 Σ Fx = 0 Σ Fy = 0 Σ Fz = 0 Condition 2 The sum of the torque, ז, is zero.
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.
Static 60° 60°
Object in free-fall Fgravity
F air friction F gravity Objects falling at constant velocity (terminal velocity)
F normal F gravity Object sliding at constant velocity(the surface is frictionless)
Object sliding without friction F normal F gravity
mass of the block = 10kg 10N 5N F applied Ff F normal 10 N 5N F gravity Is the box accelerating?
mass of the block = 10kg Σ Fy = Fnormal + Fgravity= 0 Fgravity = Weight = mass X acceleration = 10 kg X - 9.8 m/s2 = - 98 kgm/s2 = - 98 N Σ Fy = Fnormal + ( -98 N) = 0 Fnormal = 98 N F normal F applied = 10 N Ff = 5N F gravity Is the box accelerating?
mass of the block = 10kg Σ F x = Fapplied + Ff Σ 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 F gravity Is the box accelerating?
Note: There is friction between the load and the incline. • http://www.google.com.ph/imgres Draw the FBD of the box
A B C Draw the FBD of the knot (include the angle).
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.