H204 Forces Flashcards
Define a field of force.
A field of force is a region of space where a particle experiences a force.
Define centre of gravity.
The centre of gravity is the point from where all the weight of a body seems to act.
What is translational equilibrium?
A body in translational equilibrium when there is no resultant force.
State Hooke’s Law.
Hooke’s Law states that the change in length of a material is directly proportional to the force applied on it, provided that the limit of proportionality is not exceeded.
Explain proportionality limit.
The point beyond which the force applied is no longer directly proportional to the extension of the string.
Define pressure.
Pressure is defined as the force per unit area,
State the principle of moments.
Principle of moments states that for a body to be in rotational equilibrium, sum of clockwise moments about any point is equal to sum of anti-clockwise moments about the same point.
Define moment of a force.
Moment of a force about point is the product of the force and its perpendicular distance to the pivot.
Define torque of a couple.
Torque of a couple is the product of one of the forces and the perpendicular distance between the forces.
When is a body in equilibrium.
A body is in equilibrium when there is no resultant force and there is no resultant torque about any point on it.
What is a couple?
A couple is a pair of forces acting on the same body that are
(i) equal in magnitude
(ii) opposite in direction
(iii) lines of action do not coincide
