FORCE Flashcards
What is Linear or translational motion?
When a force is applied on a stationary, rigid body which is free to move the body starts to move in the direction of the applied force.
Eg: Pushing a ball lying on the floor, it begins to move in the direction of the application of force
Factors affecting moment of force
. The magnitude of force applied
. The perpendicular distance from the line of action of force to the axis of rotation
What is measurement of moment of force
The moment of force is equal to the product magnitude of force applied and the distance from the line of action of force to the axis of rotation
Unit of moment of force
Newton metre (Nm)
Unit of moment of force
Newton metre (Nm)
Relationship between SI system and CGS system for moment of force
1Nm= 10^5 + 100cm
= 10^5 + 10^2
= 10^7 dyne cm
What is a couple or what constitutes a couple
Two equal and opposite parallel forces not acting along the same line constitute a couple. A couple is needed to produce a rotation
Moment of a couple
Moment of force = either of the two forces X perpendicular distance between 2 forces
When is a body said to be in a state of equilibrium
When a number of forces acting on a body produce no change in its state of rest or linear or rotational motion the body is said to be in a state of equilibrium
What is static equilibrium give an example
When the body remains in the state of rest under the influence of several forces the body is in static equilibrium.
For example, a body is lying on a table producing a force downwards, an equal and opposite force is exerted by the table onto the book
What is dynamic equilibrium
When a body remains in the state of linear or rotational motion under the influence of several forces
How do raindrops have dynamic equilibrium
A raindrop reaches the earth with constant velocity, and the weight of the falling drop is balanced by the sum of the buoyant force and the force due to friction in air. The net force of the droplet is 0 and it falls down to the earth with constant velocity
Conditions for a body to be in equilibrium
. The resultant of all the forces acting on the body should be 0
. The algebraic sum of all the forces acting on the body about the point of rotation should be 0
Principle of moments
Principle of moments :
Sum of anticlockwise moments = sum of clockwise moments
What is centre of gravity for a body
The centre of gravity of a body is the point at which the algebraic sum of all the moments of the weights of particles constituting the body is 0. The entire weight od body is said to fall on this point
