Mechanics Flashcards
force definition
a push or pull on an object that attempts to change its motion, shape, or size
types of forces (4)
physically pushing or pulling an objects
magnets pushing or pulling
electric charges pushing and pulling
gravitational forces pulling objects together
inertia meaning
the property of an object to resist a change in motion from a force
what is inertia of an object related to?
its mass
S.I unit of forces
Newtons, N
examples of forces acting on a car
weight
friction
air resistance
reaction force
drive force
what is the resultant force
the sum of all the forces going in the same direction
weight formula
weight = mass x gravity
what is drag force and what happens to it when speed increases
drag force is an opposing force on objects moving through fluids
as speed increases the drag force also increases
force equation (related to mass and acceleration)
force = mass x acceleration
terminal velocity definition
the constant velocity of a falling object when the force of air resistance is equal in magnitude and opposite in direction to the force of gravity
equilibrium meaning
when there is zero total force applied to an object
moment of a force description
the rotational effect (turning effect) brought on a body due to application of forces
moment of a force definition
the product of the force and perpendicular distance from the pivot to the line of action of the force
moment of a force S.I. unit
Nm or Neuton metre
for anti-clockwise, use +Nm
for clockwise, use -Nm
moment formula
moment = force x perpendicular distance
principle of moments definition
it states that if a body is not to rotate, the net clockwise moment must equal the net anti-clockwise moment
spring constant equation
gradient = extension/force
spring constant = force/extension
spring constant (K) = 1/gradient
centre of gravity definition
it is the point on a body where the whole of the weight of the object is assumed to be acting
what is one thing the position of centre of gravity has an effect on
the stability of objects
elastic definition
materials that can spring back to their original shape after you bend them
3 states of equilibrium
stable equilibrium
unstable equilibrium
neutral equilibrium
plastic definition
materials that keep their new shape after you stretch or bend them
load meaning
the force applied to a spring
extension definition
the difference between a spring’s stretched and unstretched lengths
elastic limit definition
when a spring does not return to its original length or when it is left permanently stretched or deformed
limit of proportionality meaning
the point where the extension is no longer proportional to the load
what is Hooke’s Law
a material obeys Hooke’s law if, beneath its elastic limit, the extension is proportional to the load
