Unit 1 Mechanic Machine
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Transcript of Unit 1 Mechanic Machine
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The physical science which describes and predicts the condition of rest or motion bodies under the action of force.
Divided into 3 parts:1. Mechanics of rigid bodies2. Mechanics of deformable bodies3. Mechanics of fluids
• Space - associated with the notion of the position of a point. The position of the point may be defined by three lengths measured from a certain reference point, or origin in three given direction.
• Time – conceived as a succession of events.• Mass –the amount of matter in an object to which
its weight is proportional.• Force - any influence that causes a free body to
undergo a change in speed, a change in direction, or a change in shape
• Particles – a very small amount of matter which may be assumed to occupy a single point in space
• Rigid body – combination of a large number of particles occupying fixed positions with respect to each other.
Quantity Metric Unit (SI units)
1.Length Meter (m)
2.Mass Kilogram (Kg)
3.Time Second (s)
4.Force Newton (N)
Scalar – A quantity has only magnitude without direction. ( Mass, time, area, etc)
Vector- quantity that has magnitude and direction. ( force, velocity, acceleration, etc..)
Fixed vector – a vector for which a unique point of application is specified and thus cannot be moved without modifying the condition of the problem.
Free vector – a vector whose action is not confined to or associated with a unique line in space
Sliding vector – a vector for which a unique line in space (line of action) must be maintained
• First law: Every body remains in a state of rest or uniform motion (constant velocity) unless it is acted upon by an external unbalanced force
• Second law: A body of mass m subject to a force F undergoes an acceleration a that has the same direction as the force and a magnitude that is directly proportional to the force and inversely proportional to the mass, i.e., F = ma.
• Third law: The mutual forces of action and reaction between two bodies are equal, opposite and collinear. This means that whenever a first body exerts a force F on a second body, the second body exerts a force −F on the first body.
Base unit are units of length, mass and time.
SI Units length – meter (m) Mass – kilogram (kg) Time – second (s)
Derived unit Force - Newton (N) 1 N = 1kg. 1m/s2
Multiple Exponential Form
Prefix SI Symbol
1 000 000 000 109 giga G
1 000 000 106 mega M
1 000 103 kilo k
0.001 10-3 milli M
0.000 001 10-6 micro μ
0.000 000 001 10-9 nano n