Basic Physical Quantities Flashcards
(16 cards)
What are the different types of prefixes discussed in this module?
Giga, mega, kilo, milli, micro, nano, pico
What is a particle?
A “particle” is the representation of a solid that has mass but a negligible size with respect to the characteristic lengths in the system under study.
What is a rigid body?
A rigid body is a solid that has both mass and volume.
State Newton’s first axiom.
When a particle is originally at rest or moving in a straight line at a constant speed and is then subjected to a balanced system of forces, it maintains its original motion before the application of the balanced forces.
State Newton’s second axiom.
If a particle of mass m is subjected to an unbalanced system of forces of that sum to F (i.e., the resultant force is F), it moves with acceleration a in the same direction as F. The magnitude of this acceleration is proportional to the magnitude of F and inversely proportional to the mass m(a=F/m). [Remember vectors such as F and a have arrows on top to indicate it has a magnitude and a direction.
State Newton’s third axiom.
When two particles interact, each exerts a force on the other; the forces are of the same magnitude but opposite in direction. This principle is known as the principle of action and reaction.
What is the difference between a scalar and a vector?
A scalar only has a magnitude (e.g. 30s).
A vector has both magnitude and direction.
What is needed to draw a vector?
- Origin
- Direction
- Sense
- Magnitude
What is position?
Position is a physical quantity that specifies the location of a point of interest with respect to a reference point.
What is force?
The action exerted by one body on another body.
What is gravity?
Gravity is a force of attraction between any two objects with mass.
What is the difference between concentrated and distributed forces?
When a force is exerted on a part of a body that is much smaller than the body (i.e., region assimilated to a point), the force is said to be concentrated.
When a force is exerted over a considerable portion of a body (or even over the entire body) and not at a specific point or points, the force is said to be distributed.
What is the difference between external and internal forces?
A system is said to be subjected to an external force when this force is applied by any object in the environment surrounding the structure.
A system is said to be subjected to an internal force when this force is applied by any “neighboring” component belonging to the system itself.
What is the dot product?
The dot product of two vectors V1 and V2 gives a scalar number that is obtained by multiplying the magnitudes of both vectors by the cosine of the angle formed between them.
Another way to calculate the dot product is to sum the products of the individual scalar components of each vector.
What are concurrent forces?
Concurrent forces are forces that are exerted at a common point, so they have the same vector origin.
What is a resultant force?
A resultant force is a theoretical force that replaces a group of physical forces acting on a body and produces the same effect as the original group of forces.
