4.Forces Flashcards
What is Archimedes’ Principle?
The upwards force acting on an object submerged in a fluid is equal to the weight of the fluid it displaces.
Define Centre of Gravity.
The single point through which the object’s weight can be said to act.
What is the Centre of Mass?
The single point through which all the mass of an object can be said to act.
What is a Couple in mechanics?
Two equal and opposite parallel forces that act on an object through different lines of action.
Fill in the blank: Density is the _______.
mass per unit volume of a material.
What is Drag?
The frictional force that an object experiences when moving through a fluid.
What conditions must be met for an object to be in equilibrium?
Both the resultant force and resultant moment acting on the object must be equal to zero.
What is a Free-Body Diagram?
A diagram showing all the forces acting on an object.
What is Friction?
The resistive force produced when there is relative movement between two surfaces.
Define Moment of Force.
The product of a force and the perpendicular distance from the line of action of the force to the pivot.
What is the unit of force?
Newton.
State Newton’s Second Law.
The sum of the forces acting on an object is equal to the rate of change of momentum of the object.
What is the Normal Contact Force?
The reaction force between an object and surface.
What is Pressure?
The force that a surface experiences per unit area, measured in Pascals (Pa).
Fill in the blank: The Principle of Moments states that for an object to be in equilibrium, the sum of the clockwise moments must equal the _______.
sum of the anticlockwise moments.
