Section 4: Mechanics Flashcards
Difine impulse
the product of force and time. impulse on a body is equal to the change in momentum of that body.
What is the area of a force time graph equal to?
impuls (momentum change)
What is and isnt conserved in an elastic collision between two objects (in an isolated system)?
Kinetic energy - conserved
momentum - conserved
What is and isnt conserved in an inelastic collision between two objects (in an isolated system)?
momentum -conserved
kinetic energy- not conserved
What is a couple?
Is a pair of forces of equal size which act parallel to each other, but in opposite directions.
Define center of mass.
The single point through which all the mass of an object can be said to act
Difine density
The mass per unit volume of a material
What is the principal of moments?
For an object to be in equilibrium, the sum of the clockwise moments acting about a point must be equal to the sum of the anticlockwise moments acting about the point.
Breaking Stress:
The maximum stress that an object can withstand before failure occurs.
Brittle:
A brittle object will show very little strain before reaching its breaking stress.
Elastic Strain Energy:
The energy stored in an object when it is stretched. It is equal to the work done to stretch the object and can be determined from the area under a force-extension graph.
Equilibrium:
For an object to be equilibrium, both the resultant force and resultant moment acting on the object must be equal to zero.
Hooke’s Law:
The extension of an elastic object will be directly proportional to the force applied to it up to the object’s limit of proportionality.
Spring Constant:
The constant of proportionality for the extension of a spring under a force. The higher the spring constant, the greater the force needed to achieve a given extension.
Stiffness:
A measure of how difficult it is to stretch a given object
