Static of particles

Each system have the following conversion factors:

	SI system

	Symbol		Mean
	cm			centimeter
	g			gram
	slug			slug
	T			metric ton

	English system

	Symbol		Mean
	kg			kilogram
	g			gram
	in			inch
	lb/in			pounds per inch

In this module, the forces (elements Force, Friction or Resultant) are added to the objects (elements Block, Pulley, Spring and Point) placing the force in one of the cells around the object. Each object (if there isn’t in the chalkboard’s border) have 8 cells around it.

This module have 30 elements. Notice that some elements have one or two equations, depending of the applied forces. If all forces are horizontal, or vertical, the object have one equation, otherwise have two. 

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       ¬Stationary reference system

Stationary reference system, with X axis horizontal and positive to the right, and Y axis vertical an positive to upwards. 

Equations:	None.

Data:
	g:		Value of the gravity (absolute value). To default FisicaLab write the gravity
                           value to the selected system (9.81 m/s2 to SI, and 32.2 ft/s2 to English system).

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       ¬ Block

A block, allow one friction force, vertical or horizontal. And don’t allow Resultants. 

Equations:	1 or 2

Data:
	m: 		Mass block.

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       ¬ Block above an inclined plane to the left

A block, above an inclined plane to the left in the specified angle. Allow one friction force, parallel to the plane. And don’t allow Resultants.  

Equations:	2

Data:
	m:		Mass block.
	ang:		Angle of the plane, measured from the horizontal.

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       ¬ Block above an inclined plane to the right

A block, above an inclined plane to the right in the specified angle. Allow one friction force, parallel to the plane. And don’t allow Resultants.  

Equations:	2

Data:
	m:		Mass block.
	ang:		Angle of the plane, measured from the horizontal.

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       ¬  ¬  ¬  ¬Springs

Springs without mass, that satisfies the Hooke’s law. d is the length that the spring is stretched or compressed. If the spring is stretched d is positive, if is compressed is negative. Allow one or two forces. If have two forces these must have different sense (stretching or compressing the spring), and the same values or unknown data. Don’t allow frictions or resultants.

Equations:	1

Data:
	k:		Spring constant.
	d: 		Length that the spring is stretched or compressed.

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       ¬ Pulley

A pulley without mass. Don’t allow frictions or resultants.

Equations:	1 or 2

Data:
	Name:	Name of the pulley (this data is irrelevant).

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       ¬Static point

A static point without mass. Don’t allow frictions.

Equations:	1 or 2

Data:
	Name:	Name of the point (this data is irrelevant).

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       ¬ Angles

To relate two angles that must be complementary. Both angles must be unknowns.

Equations:	1

Data:
	ang1:	One angle.
	ang2:	Other angle.

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       ¬  ¬  ¬  ¬ Vertical or horizontal forces

Forces with the direction and sense of the arrow.

Equations:	None.

Data:
	f:		Magnitude of the force.

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       ¬  ¬  ¬  ¬ Oblique forces

Oblique forces with the sense of the arrow.

Equations:	None.

Data:
	f:		Magnitude of the force.
	ang:		Positive angle of the force, measured from the horizontal.

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       ¬  ¬  ¬  ¬ Vertical or horizontal friction forces
  
Friction forces with the direction and sense of the arrow.

Equations:	None.

Data:
	Normal:	Normal to calculate the friction force.
	u:		Friction coefficient, static or dynamic.

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       ¬  ¬  ¬  ¬ Oblique friction forces

Oblique frictions forces with the sense of the arrow. To be applied to a block on an inclined plane. The angle of force is the same as of the plane.

Equations:	None.

Data:
	Normal:	Normal to calculate the friction force.
	u:		Friction coefficient, static or dynamic.

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       ¬Vertical resultant    ¬Horizontal resultant

Resultants with the direction and sense of the arrow.

Equations:	None.

Data:
	f:		Magnitude of the resultant.

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       ¬Resultant

Oblique resultant.

Equations:	None.

Data:
	f:		Magnitude of the resultant.
	ang:		Angle of the resultant, measured from the positive X axis. The positive
                          sense is the opposite of clockwise.