Forces Flashcards
Define centre of gravity
Centre of gravity of a body is the single point which the whole weight of the body may be considered to act.
What are the types of non contact forces?
- gravitational field and forces
- electric field and forces
- magnetic fields and forces
What are the types of contact forces?
- normal contact force
- frictional force
- viscous force
- lift
-tension and compresssion
Define translational equilibrium
A body is in translational equilibrium if the sum of forces acting on the object in any direction is zero.
Define moment of a force
The moment of a force about a point id the product of the force and the perpendicular distance of the line of action of force to the pivot.
Define couple
A couple consists of 2 forces acting on the same body, equal in magnitude but opposite in direction whose line of action do not coincide.
Define torque of couple
The torque of couple is the product of one of the forces and the perpendicular distance between the forces.
Define rotational equilibrium
A body is in rotational equilibrium when there is no resultant torque about any point
Define POM
The principle of moments states that fir an object to be in rotational equilibrium, sum of clockwise moments about any point is equal to the sum of anticlockwise moment about that same point.
What does it mean when a body is in equilibrium?
A body is in equilibrium if
1. The sum of forces acting on the body in any direction is zero (rotational equilibrium)
2. The sum of the moments of the forces acting on the body about any point must be zero. (Rotational equilibrium)
Define upthrust
Upthrust is the net upward force exerted by a fluid on a submerged or floating object. It arises due to the difference in pressure between the upper and lower surfaces of the object.
