理论力学(双语)
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There are four concurrent cable forces acting on the bracket.
How do you determine the resultant force acting on the bracket?
1) by using parallelogram law;
F R x F xF R y F y
EXAMPLE
Given: Three concurrent forces acting on a bracket. Find: The magnitude and angle of the resultant force.
is derived from the equation.
N=
CHAPTER 2 FORCE VECTOR
These communication towers are stabilized by cables that exert forces at the points of connection. In this chapter, we will show how to express these forces as Cartesian vectors.
A) Newton’s Second
B) the arithmetic
C) Pascal’s
D) the parallelogram A vector is a quantity that has both a magnitude and a direction. Vector operations include multiplication and division by a scalarwenku.baidu.com addition; subtraction and resolution.
2.1-2.2 Vectors and Scalars
1. Which one of the following is a scalar quantity? A) Force B) Position C) Mass D) Velocity
2. For vector addition you have to use ______ law.
Coplanar Force Resultants
• Step 1 is to resolve each force into
its rectangular components
• Step 2 is to add all the x components
together and add all the y components together. These two totals become the resultant vector. Step 3 is to find the magnitude and angle of the resultant vector.
2.3 Vector Addition of Force
Two common problems in Statics involve either finding the resultant force, knowing its components, or resolving a known force into two components.
The subject is subdivided into three branches:
M e ch a n ics
R ig idB o d ie s
D e fo rm a b leB o d ie s
(T h in g sth a td on o tch a n g esh a p e ) (T h in g sth a td och a n g esh a p e )
FFx Fy FFxFy
• ThFe directions are based on the x and y axes. We use the “unit vectors” i and j to designate the x and y axes.
FFxiFyj
Cartesian
FFxiFy(j) Vector
F lu id s
S ta tics
D y n a m ics
In co m p re ssib le C o m p re ssib le
Units of Measurement
• Four fundamental physical quantities: Length, Time, Mass, and Force.
• Newton’s 2nd Law relates them: F = m * a • We use this equation to develop systems of units. • Three of four (base units) are independent and the fourth unit
Scalar Multiplication and Division
Vector Addition: Parallelogram Law Triangle method (always ‘tip to tail’) Vector Subtraction: R’ = A – B = A + (-B)
2) 2) by using the rectangularcomponent method (algebra menthod).
2.4 Cartesian Vector Notation
• We ‘resolve’ vectors into components using the x and y axes system.
ENGINEERING MECHANICS STATICS
Zheng Tinghui Ph. D DEPT. OF Applied Mechanics
SICHUAN UNIVERSITY
Mechanics
Study of what happens to a “thing” (the technical name is “BODY”) when FORCES are applied to it.
How do you determine the resultant force acting on the bracket?
1) by using parallelogram law;
F R x F xF R y F y
EXAMPLE
Given: Three concurrent forces acting on a bracket. Find: The magnitude and angle of the resultant force.
is derived from the equation.
N=
CHAPTER 2 FORCE VECTOR
These communication towers are stabilized by cables that exert forces at the points of connection. In this chapter, we will show how to express these forces as Cartesian vectors.
A) Newton’s Second
B) the arithmetic
C) Pascal’s
D) the parallelogram A vector is a quantity that has both a magnitude and a direction. Vector operations include multiplication and division by a scalarwenku.baidu.com addition; subtraction and resolution.
2.1-2.2 Vectors and Scalars
1. Which one of the following is a scalar quantity? A) Force B) Position C) Mass D) Velocity
2. For vector addition you have to use ______ law.
Coplanar Force Resultants
• Step 1 is to resolve each force into
its rectangular components
• Step 2 is to add all the x components
together and add all the y components together. These two totals become the resultant vector. Step 3 is to find the magnitude and angle of the resultant vector.
2.3 Vector Addition of Force
Two common problems in Statics involve either finding the resultant force, knowing its components, or resolving a known force into two components.
The subject is subdivided into three branches:
M e ch a n ics
R ig idB o d ie s
D e fo rm a b leB o d ie s
(T h in g sth a td on o tch a n g esh a p e ) (T h in g sth a td och a n g esh a p e )
FFx Fy FFxFy
• ThFe directions are based on the x and y axes. We use the “unit vectors” i and j to designate the x and y axes.
FFxiFyj
Cartesian
FFxiFy(j) Vector
F lu id s
S ta tics
D y n a m ics
In co m p re ssib le C o m p re ssib le
Units of Measurement
• Four fundamental physical quantities: Length, Time, Mass, and Force.
• Newton’s 2nd Law relates them: F = m * a • We use this equation to develop systems of units. • Three of four (base units) are independent and the fourth unit
Scalar Multiplication and Division
Vector Addition: Parallelogram Law Triangle method (always ‘tip to tail’) Vector Subtraction: R’ = A – B = A + (-B)
2) 2) by using the rectangularcomponent method (algebra menthod).
2.4 Cartesian Vector Notation
• We ‘resolve’ vectors into components using the x and y axes system.
ENGINEERING MECHANICS STATICS
Zheng Tinghui Ph. D DEPT. OF Applied Mechanics
SICHUAN UNIVERSITY
Mechanics
Study of what happens to a “thing” (the technical name is “BODY”) when FORCES are applied to it.