Force Flashcards
a rigid body when acted upon by a force has two motions
- translational
- rotational
factors affecting turning of a body
magnitude of a force applied
perpendicular distance between the line of action of a force from the axis of rotation.
define torque
product of the magnitude of force and the perpendicular distance between the line of action of force from the axis of rotation
how to change direction of a rotating body
changing point of application of force
changing direction of force
define couple
the pair of forces, formed by the external force and the force of reaction is called a couple.
TWO EQUAL AND OPPOSITE PARALLEL FORCES NOT ACTING ALONG THE SAME LINE, FORM A COUPLE.
a couple is always needed to produce a rotation.
formula of moment of couple
product of either force and the perpendicular distance between the two forces.
conditions for equilibrium of body
- resultant of all forces should be zero
- algebraic sum of all moments of all the forces about the fixed point is zero.
define equilibrium
a body preserving its state (static or dynamic) in the presence of two or more forces.
types of equilibrium
static and dynamic
principle of moments
if the algebraic sum of the moments of all the forces acting on the body, about the axis of rotation is zero, the body is in equilibrium .
sum of anticlockwise moments= sum of clockwise moments
define centre of gravity (CG)
the point about which the algebraic sum of moments of all weights of all particles constituting the body is zero.
difference between uniform circular and uniform linear motion
uniform linear: speed constant, velocity constant, no acceleration
uniform circular: speed constant, velocity not constant, variable acceleration there
define centripetal force
the force acting on a body moving in a circular path, in a direction towards the centre of the circular path
define centrifugal force
a force assumed to be acting on the body in a direction away from the centre of circular path.
it is in opposite direction to centripetal force. it is not real.
