Forces and Moments Flashcards
define force
force is directly proportional to rate of change of momentum
define field of force
region of space where force is felt
define hooke’s law
force is directly proportional to extension, provided that the elastic limit has not been exceeded
define pressure
force per unit area
define elastic limit
point which spring does not return to its original length when load is removed
define hydrostatic pressure
pressure at certain depth or point in a liquid
define density
mass per unit volume
define drag force
frictional force experienced by an object as it moves through fluid or by a fluid as it moves over a surface
define frictional force
force exerted by one body on another body when two bodies slide over one another. it is caused by irregularities in the surfaces in mutual contact and depends on the surfaces in contact as well as how much they are pressed against each other. it is the component of contact force along surfaces of contact
define tensile forces
2 forces acting in opposite directions on an object so as to tend to increase its length along the direction of forces
define comprehensive force
2 forces acting in opposite directions on an object so as to tend to reduce its length along direction of forces
define conservative force
a force is conservative if the work it does on an object moving between 2 points is independent of the path the object takes.
define non-conservative force
a force is conservative if the work it does on an object depends on the path taken by an object between it’s initial and final points.
define equilibrium
No resultant force acting on the body in any direction and no resultant moment acting on the body about any point
define centre of gravity
single point at which the entire weight of the body can be considered
define centre of mass
mean location of all the mass in a system. It is the point through which a single force must act for the object to accelerate linearly without any rotation
define moment of a force
moment of a force about a point is the product of the magnitude of the force and the perpendicular distance of the force from the point.
define couple
consist of a pair of forces equal in magnitude but acting in opposite directions whose lines of action are parallel but separate
define torque of a couple [MUST INCL DEF of COUPLE as well]
product of one of the forces and the perpendicular distance between the forces + [Definition of couple]
principle of moments
when a system is in equilibrium, the sum of clockwise moments about any point is equal to sum of anticlockwise moments about the same point.
define terminal velocity
constant velocity achieved by an object when it is falling under gravity through a viscous fluid
2 conditions for a body in equilibrium
resultant force on it must be 0 in any direction
resultant torque on it must be 0 about any axis of rotation
When is a body said to be in translational equilibrium
when resultant force is 0 in any direction, no acceleration of its centre of mass
