INTRODUCTION .edu
INTRODUCTION
ENGINEERING AND MECHANICS
MECHANICS - the study of forces and their effects
STATICS - the study of objects in equilibrium
DYNAMICS - the study of objects in motion
LEARNING MECHANICS
The main goal - understand the principles well enough to apply them to new situations
Problem Solving:
- Identify the information that is given and the information/answer to determine
- Develop the strategy – identify the principles and equations to apply, and draw diagrams if possible
- Try to predict the answer
- Solve the equations and interpret results (and compare them with the prediction)
Engineering Applications
Essential aspects of engineering:
- Design (choose values of parameters to satisfy stated design criteria)
- Safety (choose values of parameters to satisfy stated safety requirements)
Fundamental Concepts
Numbers
Engineering measurements, calculations and results are expressed in numbers.
Space and Time
|Space |– |geometric region occupied by bodies whose positions are described by linear and angular measurements relative to a coordinate system. |
|Time |– |measure of the succession of events; basic quantity in dynamics, not directly involved in statics. |
|Mass |– |measure of the inertia of a body (resistance to a change of a velocity), or the quantity of matter in a body; also, the property of every body by which it experiences |
| | |mutual attraction to other bodies. |
|Force |– |action of one body to another; tends to move a body in the direction of its action; vector quantity. |
|Particle |– |body of negligible dimensions (may be analyzed as a point mass) |
|Rigid body |– |relative movements between its part are negligible for the purpose in hand |
Newton’s Laws
|I |– |A particle remains at rest or continues to move in a straight line with uniform velocity if there is no unbalanced force acting on it. |
|II |– |The acceleration of a particle is proportional to the resultant force acting on it and is in the direction of this force. |
|III |– |The forces of action and reaction between interacting bodies are equal in magnitude, collinear, and opposite in direction. |
UNITS
| |Dimensional |SI Units |U.S. Customary Units |
|Quantity |Symbol |unit |symbol |unit |symbol |
| Mass |M |Base units|kilogram |kg | |slug |- |
| Length |L | |meter |m |Base units|foot |ft |
| Time |T | |second |s | |second |s |
| Force |F | |newton |N | |pound |lb |
Derived units: 1 N = 1 kg-m/s2 SI Units
1 slug = 1 lb-s2/ft U.S. Customary Units
The common prefixes used in SI units and the multiples they represent
|Prefix |Abbreviation |Multiple |
| pico- |p |10-12 |
| nano- |n |10-9 |
| micro- |μ |10-6 |
| mili- |m |10-3 |
| kilo- |k |103 |
| mega- |M |106 |
| giga- |G |109 |
| tera- |T |1012 |
Angular Units
|Quantity |unit |symbol |unit |symbol |
|Angle |radian |rad |degree |( or deg |
Conversion of Units
|Length |1 in |= |25.4 mm |
| |1 ft |= |12 in |
| | |= |0.3048 m |
| |1 mi |= |5280 ft |
| | |= |1609 m |
| |1 m |= |3.281 ft |
| |1 km |= |0.6214 mi |
|Time |1 min |= |60 s |
| |1 hr |= |60 min |
| |1 day |= |24 hr |
|Mass |1 slug |= |14.59 kg |
| |1 kg |= |0.0685 slug |
|Force |1 lb |= |4.448 N |
| |1 N |= |0.2248 lb |
|Angle |2 π rad |= |360( |
| |1 rad |= |57.3( |
| |1( |= |0.01745 rad |
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Both 䥓愠摮唠匮畃瑳浯牡⁹湵瑩൳
SI and U.S. Customary units
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